TS 650 
 .F5 
 
LIBRARY OF CONGRESS. 
 
 Chap. Copyright No. 
 
 Shelf.^E_£_ 
 
 UNITED STATES OF AMERICA. 
 
GALVANIZING 
 
 AND TINNING 
 
 A Practical Treatise on Coating with Tin and Zinc 
 
 WITH A 
 
 Special Chapter on Tinning Gray Iron Castings 
 
 BY 
 
 W. T. KLANDKRS 
 
 PUBLISHED BY DAVID WILLIAMS COMPANY 
 
 232-238 William St., New York 
 
 1900 
 
63375 
 
 Litunu^f. of Con^Treea 
 
 I'v^ CuftLij Received 
 OCT 19 1900 
 
 Cofvrighl entry 
 
 SLCOND COPY. 
 
 0(ftiver«d to 
 
 ORDt« DIVISION, 
 OCT 25 1900 
 
 i^ |;i 
 
 Copyrighted 1900 
 By David Williams CoMPA>rY 
 
 i 
 
 y / 
 
In 1876 the firm I was employed by, finding it neces- 
 sary to galvanize the goods they were manufacturing, 
 placed the matter in my hands. Having little or no 
 knowledge of the process, I spent considerable money in 
 buying technical books that purported to treat on the 
 subject, but found that what little they had to say was of 
 no practical value whatever. I think the same condi- 
 tions prevail now. Since 1889 I have made the installa- 
 tion of galvanizing and tinning plants a business and have 
 built nearly sixty. The increased demand for galvanized 
 and tinned goods within the last ten years has brought 
 me many requests from people for information regard- 
 ing the two processes, and some four years ago I gave a 
 brief description of the process of galvanizing in The 
 Iron Ace and The Metal Worker. At the request of 
 the publishers I have undertaken to describe the different 
 methods of coating with zinc and tin by immersion. 
 Having no previous work on the subject as a guide and 
 being w^hoUy unused to writing, I realize that my work 
 lacks the finish of most technical books. I think, however, 
 that my treatment of the several subjects, coupled with the 
 illustrations given, will enable one to make a successfui 
 start in any of the processes. 
 
 W. T. Flanders. 
 
 Nashua. N. He 
 
CONTENTS. 
 
 Page, 
 
 Galvanizing j 
 
 Locating a Plant and Selecting a Kettle 8 
 
 The Galvanizing Room 8 
 
 Tanks for Acids and Other Purposes lo 
 
 Tools for Galvanizing 1 1 
 
 Filling and Firing a New Kettle 13, 
 
 The Use of a Pyrometer 13 
 
 Materials Used in Galvanizing 14 
 
 Building and Setting Kettles 15 
 
 Removing vScale with Sulphuric Acid 23 
 
 Cleaning Sandy Castings with Sulphuric Acid .... 24 
 
 Preparing the Work for Dipping in the Zincing 
 
 Bath 25 
 
 Drying the Work 25 
 
 The Heat of Zinc 27 
 
 Dipping the Work in the Molten Metal 29 
 
 The Formation of Dross in the Kettle 36 
 
 Running Over, or " Sweating," Zinc Dross . 39 
 
 Tinning Malleable Iron, Wrought Iron and Steel 43 
 
 Preparing the Work 44 
 
 Tools and Kettles 45 
 
 A Tinning Plant 46 
 
 Plan of Tinning Plant 48 
 
 Removing Scale and Rust with Sulphuric Acid .... 50 
 
Page. 
 
 Cleaning Sandy Castings by Sulphuric Acid 52 
 
 Cleaning Sandy Castings with Hydrofluoric Acid . . 52 
 
 Removing Paint or Grease 53 
 
 Tinning with a Single Kettle of Tin 54 
 
 Tinning with Two or More Kettles of Tin 55 
 
 Passing the Work Through the Tinning Kettles. . 56 
 
 Tinning Wire in Coils 5^ 
 
 Tinning Steel Spoons and Similar Articles 59 
 
 Retinning 60 
 
 Setting Retinning Kettles 64 
 
 Tinning Common Gray Iron 66 
 
 Description of Tinning Plant 67 
 
 General Considerations 69 
 
 Tumbling Barrel 70 
 
 Freeing Gray Iron Castings from Sand by Hydro- 
 fluoric Acid 74 
 
 Cleaning Sandy Castings with Sulphuric Acid. . . . 77 
 
 The Use of a Hot Alkali Bath in Certain Cases .... 78 
 
 Preparing the Castings in the Gas Barrel 78 
 
 Coating the Castings with Tin 83 
 
GALVANiZiNG. 
 
 The coating of articles of iron and steel with zinc, or^ 
 
 as the process is generally known, *' galvanizing " them, 
 as a means of retarding oxidation and for other reasons, 
 has become a vast industry, in which a large number of 
 men find employment. 
 
 It is not our purpose to attempt a description of the 
 methods emplo}'ed by the great manufacturers of gal- 
 vanized sheets and wire, but to confine our efforts to the 
 requirements of those who wish to engage in the business 
 in a small way and to enable those whose location would 
 otherwise compel them to ship goods long distances to 
 erect and operate a plant of their own. 
 
 It may not be out of place to say that it has been the 
 practice of some engaged in the business to make as 
 much of a mystery of it as possible. One fallacy given 
 out and generally credited is that a galvanizing kettle 
 must not be allowed to cool off. This, perhaps, has de- 
 terred a greater number from attempting their own work 
 than anything else. While it is true that it is not prac- 
 ticable to allow a kettle holding several tons of metal to 
 cool off every few days, there is no reason why a kettle 
 containing a few hundred pounds of metal cannot be al- 
 lowed to cool when it is not required for use. 
 
 While it is our purpose to treat the subject in a way 
 that will give a general idea of the whole business, our 
 efforts will be mostly confined to explaining the methods 
 
 T 
 
8 GALVAXIZIXG AND TIXXIXG. 
 
 to be employed in galvanizing castings of gray and mal- 
 leable iron, small articles of wrought iron and steel and 
 sheet metal goods. 
 
 LOCATIXG A PLAXT AXD SELECTING A KETTLE. 
 
 To those contemplating the installation of a galvaniz- 
 ing plant the first question that naturally comes up is, 
 where can it best be located? In settling this question it 
 should be kept in mind that the fumes of the chemicals 
 used in the business are destructive to tools and machin- 
 ery. For this reason the galvanizing plant should be in a 
 building by itself. 
 
 The next question is, what size kettle should be used 
 and what is the best material to make it of ? On account 
 of the difficulty in controlling the heat of a small body of 
 metal, we would not advise the use of a kettle, for any 
 purpose, less than 3 feet in length, 20 inches in depth and 
 18 inches in width. The material for the kettle should be 
 refined iron or best fire box steel, and should not be less 
 than Yz inch thick. 
 
 THE GALVAXIZIXG ROOM. 
 
 In providing a room or a building in which to locate 
 the plant, provision should be made to obtain good ven- 
 tilation. It should be high posted and have a good ventila- 
 tor in the roof, and if the character of the work to be 
 done will admit, a hood may be built over the kettle, com- 
 ing low enough to catch all the smoke possible, while not 
 interfering with the movements of the operator. When 
 the work is castings or small articles, there is no objection 
 to having the hood come to within 6 feet of the floor, and 
 it should be at least 2 feet larger than the brick work sur- 
 rounding the kettle. 
 
GALVAXIZIXG. 
 
 Considerable water is used in the process, and provi- 
 sion should be made to secure proper drainage. A good 
 
 Fig. 1.— Floor Plan of Galvanizing Room. 
 
 plan is to put in a cement floor, which can be laid so as to 
 provide gutters on each side of the room. If the work to 
 
lO GALVANIZING AND TINNING. 
 
 be handled is castings it is not absolutely necessary to 
 use steam, but if the work is of a nature that requires the 
 removal of scale, steam should be brought into the room. 
 A floor space 25 x 50 feet will accommodate such an 
 outfit as we illustrate by Fig. i. A much less floor space 
 can be made to accommodate a very small plant. Fig. i is 
 the ground plan of a galvanizing plant, in which A is a 
 tank for containing a solution of sulphuric acid and water 
 for removing scale and rust. B is a water tank for stor- 
 ing work that has been cleaned. C is a platform where 
 castings are placed to free them from sand. D is a tank 
 used to contain the solution for removing the sand from 
 the castings after they have been placed on the platform. 
 E is a tank for muriatic acid. F is the plate for drying 
 the work before immersing it in the molten metal. G is 
 the kettle containing the metal and H is the tank used for 
 cooling the work after it is coated with the zinc. I I in- 
 dicate the loose planks covering the ash pits, shown in 
 Fig. 3 as M INI. K is an underground flue connecting the 
 drying plate F with a chimney or stack. L, and M is a pit 
 to give access to the ash pit under the plate F. 
 
 TANKS FOR ACIDS AND OTHER PURPOSES. 
 
 The illustration, Fig. i, shows wooden tanks, to be 
 built as shown in Fig. 12. When this style of tank is em- 
 ployed the bolts, in those designed for acid, should be of 
 •copper. Pine or cypress makes good material for tanks. 
 It is by no means necessary to build expensive tanks if 
 the work to be done is small articles. If oil barrels are 
 sawed in half and thoroughly cleaned they answer every 
 purpose, provided, of course, that the work is of a size 
 that half barrels will accommodate. 
 
 It used to be considered necessarv to line acid tanks 
 
GALVANIZING. 
 
 II 
 
 with lead. The experience of the writer is that it is 
 money thrown away. The practice has been almost en- 
 tirely abandoned. 
 
 TOOLS FOR GALVANIZING. 
 
 The tools employed in galvanizing usually consist of 
 tongs of various shapes and sizes, baskets of sheet iron or 
 heavy wire cloth, and wires bent in various shapes. The 
 necessary shape of the tongs will be suggested by the 
 
 Fig. S. — Top View of Large Galvanizing Kettle. 
 
 shape of the article to be handled. In Fig. 13 we illus- 
 trate the shape of baskets and wires most generally in 
 use. B is a sheet iron basket having a handle about 3^ 
 feet long. 1 he basket should be about 8 inches in diam- 
 eter at the top and 7 inches at the bottom, with a depth of 
 9 inches. Both the bottom and body should be well per- 
 forated to allow the metal to pass out. This style of 
 basket is well adapted to galvanizing nails and other small 
 articles, and the holes should be of a size that will not ad- 
 
12 
 
 GALVANIZING AND TINNING. 
 
 mit of the articles being handled falling through. A is 
 a basket made of heavy wire cloth, the body being about 
 8 inches wide, lo inches long and 6 inches deep. This 
 basket is adapted to large work that cannot be strung on 
 wires and is too small to be handled singly with tongs. 
 
 M 
 
 M 
 
 'i\^^^////} 
 
 ^ 
 
 
 c c 
 
 Fig. S.— Section of Fig. 2 at A\ A\ 
 
 Fig. 4.—Side Elevation of Large Galvanizing Kettle 
 
 E and G are wires for handling small work in the molten 
 metal. F is a scoop for removing the dross from the bot- 
 tom of the kettle. D and H are skimmers, and E is a hook 
 to suspend in the molten metal articles that are strung on 
 wires. The use of all will be explained in their turn 
 
GALVAXI.ZIXG, 13 
 
 Most of these tools are adapted to use in tinning as well 
 as galvanizing. 
 
 FILLING AND FIRING A NEW KETTLE. 
 
 In filling a kettle for the first time with the pigs of 
 zinc, or, as it is termed in the trade, " spelter," place the 
 metal in a way that it will lie as closely as possible to the 
 sides of the kettle, and also arrange it so that as the 
 outside slabs of metal melt those next to them will be 
 forced against the sides of the kettle. Unless this is done 
 the kettle is apt to be injured by the heat. Do not allow 
 the fires to burn too freely in melting a kettle of zinc or 
 in firing up a kettle that is full of cold metal. In melting 
 a kettle of metal for the first time keep the fires about even 
 with the molten metal in the kettle, allowing them to rise 
 in about the same proportion as the metal melts. Do not 
 use the top drafts until the molten metal is about even 
 with them. 
 
 THE USE OF A PYROMETER. 
 
 A good pyrometer placed in the kettle will be found 
 of great value in keeping the bath at a uniform temper- 
 ature. Unless, however, the stem of the pyrometer is 
 protected from the action of the metal it will soon be de- 
 stroyed. The writer has devised a means by which the 
 stem of the pyrometer is kept from contact with the 
 molten zinc and at the same time gives the same result as 
 though the molten zinc w^as in direct contact with the 
 pyrometer stem. 
 
 The arrangement consists of a piece of 2-inch pipe 
 about 20 inches long, with one end closed tight. The top 
 of the pipe is provided with a bushing, with a hole a little 
 larger than the stem of the pyrometer. A second bushing 
 should also be placed in the pipe about 3 inches from the 
 
14 
 
 GALYANIZINr. AND TTMMTMn 
 
 bottom. These bushings serve to keep the pyrometer in 
 an upright position. The casing surrounding the stem of 
 the pyrometer is filled with lead, so that when the arrange- 
 ment is placed in the kettle there is a direct metal connec- 
 tion with the stem of the pyrometer. Fig. 14 shows a py- 
 rometer in position in the kettle, while Fig. 15 shows the 
 " protector " in detail. 
 
 MATERIALS USED IN GALVANIZING. 
 
 The principal materials used in galvanizing are zinc. 
 
 Fig. 5 — Section at Grate Line of Large Oalvamzing Kettle 
 
 sal ammoniac, muriatic, sulphuric and hydrofluoric acids 
 and gas coke. We cannot with fairness express a prefer- 
 ence for any brand of spelter, and will only say, use spel- 
 ter smelted by a reliable firm, keeping in mind that much of 
 the so-called spelter is recovered from zinc dross by par- 
 ties who do not have the facilities for doing the \vork 
 properly. The best sal ammoniac to use is the " gray 
 granulated," although the " white granulated " answers 
 every purpose. 
 
GALVANIZING. 
 
 15 
 
 BUILDING AND SETTING KETTLES. 
 
 In deciding what size kettle to put in you must be 
 guided by the nature of the work to be done. If it is 
 small articles that are to be handled, and the amount such 
 
 O 
 
 O) 
 
 ■\2y 
 
 c 
 
 ^ 
 
 E 
 
 K 
 
 Et- 
 
 Lt,;;, " ■■{ 
 
 Uj 
 
 I^ 
 
 H 
 
 Fig. 6.— Casting Details of Large Galvanizing Kettle. 
 
 as will only require the plant to be operated at intervals, 
 a kettle 3 feet long, 18 inches wide and 20 inches deep 
 will answer the purpose. A kettle more than 20 inches 
 deep makes it necessary to provide ash pits at the sides, 
 as shown in Fig. 3 and designated M M. 
 
 n^ 
 
i6 
 
 GALVANIZING AND TINNING. 
 
 In Figs. 7, 8 and 9 we show method of setting a small 
 kettle that is not designed to be operated continually. The 
 grates C C in Fig. 9 are bars of iron that may be with- 
 drawn when it is desired to let the fire out and replaced 
 when required for use. 
 
 Figs. 2, 3, 4 and 5 show manner of setting kettles 5 feet 
 long and upward, and Fig. 6 gives the casting details. 
 Fig. 10 gives shape and construction of kettle. The rivet- 
 
 
 
 
 A 
 
 
 I i . 
 
 A 
 
 
 . 
 
 -H a 
 
 
 1 1 
 
 1 1 
 1 1 
 1 > 
 
 1 1 
 
 
 Fig. 7. — Top Plan of Small Galvanizing Kettle. 
 
 ing in the heads may be spaced 2J/2 inches, while the 
 rivets securing the stiffening bars to the sides may be 
 spaced 4 inches. For kettles from 4 to 6 feet in length 
 material % inch thick will answer for the body and ^ 
 inch for the heads. Above 6 feet material at least i inch 
 thick should be used. 
 
 Fig. 10 shows a kettle in which the body is formed of 
 one piece, and with the rivets where the fire will not affect 
 them. A kettle for general use built after this illustration 
 
GALVANIZING. 
 
 17 
 
 is our preference for many reasons, but it does not follow 
 
 that the work could not be done in a kettle of any shape. 
 
 A, Fig. 6, are the coping plates, the position of which 
 
 is shown in Figs. 2, 3 and 4. These plates, when held in 
 
 Fig. 8.— Section of Fig. 7 at A', A, 
 
 Fig. 9. — Section of Small Galvanizing Kettle, Showing Method 
 
 of Setting Grates. 
 
 place by the bolts C, serve to preyent the sides of the 
 kettle from springing outward when the iron blocks D D 
 are in place, as shown in Figs. 2 and 3. Coping plates 
 for kettles from 4 to 6 feet long should be 2y^ inches 
 
i8 
 
 GALVANIZING AND TINNING. 
 
 thick and lo inches wide. The fire spaces E E in Figs. 2 
 and 3 should not be more than 7 inches wide and the same 
 length as the inside of the kettle. 
 
 D in Fig. 6 are the blocks designated in Figs. 2 and 3 
 as D. F in Fig. 6 are the iron plates i inch thick. Their 
 positions are designated in Figs. 2 and 3 as F. G in Fig. 
 6 is a section of grate, the position of which is designated 
 in Figs. 3 and 5 as G G. The openings of this grate 
 should be about i inch wide and the grates should be wide 
 
 Fig. 10. — End and Side Elevations and Top View of Large 
 Galvanizing Kettle. 
 
 enough to span the fire spaces E E in Figs. 2 and 3 and 
 rest on plates H H and the pier I, on which the kettle B 
 rests, as shown in Fig. 3. The plate H in Fig. 6 may also 
 be used to cover the fire spaces E E, Figs. 2 and 3. The 
 plates should be about 3^ inch thick and 12 inches wide; 
 their length is determined by the length of the kettle. K 
 in Fig. 6 is the casing for the upper draft holes indicated 
 as K K in Figs. 3 and 4. The casing should be about 10 
 inches long, with the opening about 4x4 inches. It 
 should be arranged to close with a slide, as shown in Fig. 
 
GALVANIZING. 
 
 19 
 
 4. L in Fig. 6 shows the casings for the lower set of 
 drafts, the openings in which should be 8 x 12 inches. 
 Their position in the brick work is designated in Figs. 3, 
 4 and 5 as L. Fig. 2 is a top plan of the brick work. Fig. 
 3 is a vertical section at A' A' and Fig. 4 is a side ele- 
 vation. 
 
 The ash pits M M, in Fig. 3, should be about 2 feet 
 wide. The pits are covered with loose planks, so that 
 access to the lower drafts may be had for the purpose of 
 
 000 
 
 Fig. 11. — Casting Details of Small Galvanizing Kettle. 
 
 opening or closing them, and also for the purpose of re- 
 moving the ashes from the spaces N N under the grates 
 G G, Fig. 3. 
 
 Fig. 5 is a horizontal section of the brick work at the 
 grate line and shows the grates G G in position, and also 
 the manner of laying the bricks between the draft casings 
 L L. I indicates the pier on which the kettle rests. It 
 will be seen that the brick work between the lower draft 
 casings L L is built in a way to allow all the access possi- 
 ble to the grates G G from the ash pits M M. The plates 
 
20 
 
 GALVANIZING AND TINNING. 
 
 H H are used to test the outer edge of the grates G G on, 
 and also to support the brick waUs at each side of the 
 kettle. The walls on each side of the kettle should have 
 a lining of fire brick commencing at the grate and ex- 
 tending upward to the coping plates A A, Fig. 3. 
 
 Figs. 7, 8 and 9 show manner of setting a kettle that 
 is not deep enough to require ash pits at the sides. For 
 
 ■i i 
 
 J 
 
 Fig. 13.— Details of Acid Tank. 
 
 casings for the upper and lower drafts make the patterns 
 as shown in Fig. 6 and which are designated K and L. 
 Fig. 7 is a top plan of the brick w^ork surrounding the ket- 
 tle. Fig. 8 is a vertical section of Fig. 7 at A' A', and 
 Fig. 9 is a horizontal section at B' B'. 
 
 Fig. 6 shows all the casting details necessary to set a 
 kettle in the manner shown in Figs. 2, 3, 4 and 5. The 
 bolt C that sets in the brick work vertically is provided 
 at one end with a foundation washer, B, which is held in 
 place by the key E, The positions of the other castings 
 
GALVANIZING. 
 
 21 
 
 in this figure are all shown by corresponding letters in 
 Figs. 2, 3, 4 and 5. 
 
 Fig. II gives the casting details necessary to set a ket- 
 tle after the plan shown by Figs. 7, 8 and 9. A is a plate 
 
 Fig. 13 — Galvanizing Tools. 
 
 to cover the top of the brick work surrounding the kettle, 
 and its position is designated in Fig. 7 as A. B is a cast- 
 ing used in connection with bolts passing through the ends 
 to bind the brick work together. Its position is desig- 
 nated in Fig. 8 as B. C is the grate, the position of which 
 is shown in Fig. 9 at C, and D, Fig. 11, are the castings 
 
22 
 
 GALVANIZING AND TINNING. 
 
 for supporting each end of the grates C, the position of 
 which is designated in Figs. 8 and 9 by D. 
 
 A kettle for galvanizing pipe should be 23 feet long, 
 3 feet deep and 2 feet wide. One for sheet iron ware, if 
 it is intended to include washtubs and garbage cans, 
 should be 6 feet long, 3 feet wide and 4 feet deep. Coal 
 hods can be galvanized in a kettle of the size shown in 
 
 Fig. 14. — Perspective of Oalvanizing Kettle, Showing 
 Position of Pyrometer. 
 
 Fig. 2 — viz., 6 feet long, 3 feet deep and 18 inches wide. 
 A kettle designed especially for galvanizing wire should 
 be II feet long, 2 feet deep and 2 feet wide. Wire cloth 
 and poultry netting is best run in a kettle 6 feet long, 4 
 feet wide and 2 feet deep. 
 
 In bricking in a kettle use care to protect all the calked 
 joints from the fire and do not make the fire spaces too 
 wide. If too much space is left for fire the heat of the 
 metal cannot be kept under control. 
 
GALVANIZING. 
 
 23 
 
 REMOVING SCALE WITH SULPHURIC ACID. 
 
 Nearly all articles made of wrought iron or steel or of 
 sheet metal are covered with more or less heavy scale, 
 which must be completely removed before the zinc will 
 
 Fig. 15. — Pyrometer " Protector " in Detail 
 
 adhere. To accomplish its removal make a pickle of 
 sulphuric acid and water, i part acid to 20 of water, and 
 bring the solution to a temperature of about 150 de- 
 grees F. 
 
 The length of time required to accomplish the work 
 
24 GALVANIZING AND TINNING. 
 
 varies with the thickness of the scale. In many cases it 
 is necessary to remove part of it with some sharp pointed 
 tool. When the material has been burned in welding, 
 and where the scale has been rolled deeply into the stock, 
 it is necessary to use a tool to loosen the scale. Stock 
 having an uneven coating of scale should be cleaned in a 
 w^eaker solution than that having an even coating or than 
 that having a light scale. The reason is that that part 
 of the stock which is first made clean will be overpickled 
 before the parts having the heavier scale are clean. 
 
 When the work seems perfectly clean and free from 
 scale or rust it should be put into a tank containing water 
 enough to cover it completely. A, in ¥ig. i, designates 
 the tank to be used for treating the material to remove 
 the scale, and B in the same illustration denotes the stor- 
 age tank. 
 
 CLEANING SANDY CASTINGS WITH SULPHURIC ACID. 
 
 Castings that are sandy may be cleaned by pouring 
 over them a solution of sulphuric acid and water, i part 
 acid to 6 of water. Place the castings on the platform 
 C in Fig. I and wet them with the solution which is con- 
 tained in tank D, Fig. i. Continue this operation until 
 the sand will wash ott by the application of water. The 
 castings should be wet every hour or so, and they should 
 be cleaned in about 12 hours. 
 
 Cast iron that has been allowed to remain in the pickle 
 too long will be covered with a gummy or greasy sub- 
 stance, and will not properly take the coating of zinc un- 
 less it is left in the metal a long time, and even then it will 
 not be nicely coated, but will be rough and covered with 
 thick patches of metal. It will not have the gloss that a 
 properly prepared casting will have. We refer to this 
 
GALVANIZING. 2^ 
 
 method of cleaning sandy castings in the chapter on tin- 
 ning, and it will be well to read what is said there in this 
 connection, as the rules there given apply to galvanizing, 
 as well as what is said regarding dry tumbling as an aid 
 in cleaning work for tinning. 
 
 PREPARING TIIK WORK FOR DIPPING IN THE ZINCING 
 
 BATH. 
 
 To enable the zinc to take to the work quickly and 
 firmly a solution of muriatic acid and water is used. This 
 not only serves as a flux, but it removes any rust that has 
 formed on the work in the operation of inspecting and 
 removing the scale or sand that the sulphuric acid pickle 
 failed to remove. If the work has been thoroughly 
 cleaned by dry tumbling the use of sulphuric acid is not 
 necessary. If no rust has formed on the work all that is 
 necessary is to immerse it for two or three minutes in this 
 muriatic solution. If rust is present it must be immersed 
 long enough to remove it. 
 
 Some galvanizers use full strength acid for this pre- 
 paratory dip, but we prefer to dilute the acid about one- 
 half and to add i pound of sal ammoniac to a gallon of the 
 mixture. Tank E, Fig. i, is for containing this mixture. 
 
 DRYING THE WORK. 
 
 From tank C, Fig. i, or, in other words, from the 
 muriatic acid, the work is taken to the place provided for 
 drying it. The position of this drying arrangement is 
 designated F in Fig. i. This drying arrangement may 
 be the plates covering the fires that heat the kettle. If 
 the work to be handled only amounts to a few hundred 
 pounds per day it can be dried in this way. If, however, 
 the amount of work necessitates keeping the kettle in con- 
 
26 
 
 GALVANIZING AND TINNING. 
 
 stant Operation, a drying arrangement such as shown ia 
 Figs. i6, 17 and 18 should be provided. Sheets and pipe 
 should be dried in an oven. 
 
 Fig. 16. — Perspective View of Drier. 
 
 Fig. 17 .—Horizontal Section of Fig. 16 at Orate Line, 
 
 •mzmzs2^zs:2Z2. 
 
 
 
 Fig. 18.— Vertical Section of Fig, 16. 
 
 The location of this drying arrangement is a mere 
 matter of choice. In Fig. i we show it located at one 
 end of the kettle. The work should be perfectly dry, but 
 it should not be allowed to get hot enough to burn the 
 
GALVANIZING 21 
 
 acid. When properly dried the muriatic acid should 
 show on the surface of the work in the form of a white 
 powder. Work that has been prepared for dipping and 
 dried should not be allowed to get cold, and if more has 
 been prepared for dipping than can be finished it should 
 not be allowed to remain on the drier over night, but re- 
 turned to the water tank. It should, of course, be re- 
 dipped in the muriatic solution and dried again before 
 putting it into the zincmg kettle. 
 
 Figs. i6, 17 and i8 show a good arrangement for 
 drying the work. Fig. i6 is a perspective view of the 
 completed work, Fig. 17 is a horizontal section of Fig. 16- 
 at grate, and Fig. 18 is a vertical section. 
 
 THE HEAT OF THE ZINC. 
 
 This part of the business is not only the most difficult 
 to describe, but it is the most difficult to learn, for the 
 reason that different kinds of work require that differ- 
 ent temperatures be maintained. A kettle of zinc at the 
 proper heat for wire or wire cloth would be much too hot 
 for galvanizing castings of either gray or malleable iron, 
 while with the zinc at the proper heat for large work it 
 would be impossible to coat small work properly, even if 
 the material was the same. Large pieces require that a 
 low heat be maintained on the zincing bath. Small work 
 that is strung on wires for dipping requires a higher heat 
 of the zincmg bath than heavy pieces. Work that is gal- 
 vanized in baskets requires a higher heat of the zincing 
 bath than work that is strung on wires and drawn from 
 the coating bath without the aid of a flux on the surface 
 of the molten metal, as hereafter described. 
 
 We shall give the degrees of heat that a pyrometer 
 should indicate when different kinds of work are being 
 
28 GALVANIZING AND TINNING. 
 
 done, basing the rules given on the supposition that when 
 the metal is barely melted — that is, at a temperature that 
 would just keep it in a liquid state, the pyrometer indicates 
 750 degrees of heat. We shall also give the best rules 
 possible for determining the proper temperature by the 
 looks of the metal and by other signs. 
 
 Large gray iron castings require that the metal be at 
 the lowest temperature possible and have it liquid. At 
 about this temperature it will be silver white in color, will 
 burn sal ammoniac slowly when thrown on its surface, and 
 when a skimmer is passed over its surface the oxide will 
 be slow in appearing. In this condition the pyrometer 
 should indicate about 775 degrees of heat. This tem- 
 perature is also suitable for galvanizing very thin castings 
 that it is designed to " spangle " or to have a crystallized 
 appearance — for example, sinks and like work. 
 
 For small castings that are to be drawn through the 
 metal without using a flux the pyrometer should indicate 
 about 840 degrees. At this temperature the metal should 
 have a slightly bluish cast, burn sal ammoniac moderately 
 quick and show the oxide in a few seconds after the 
 skimmer has been passed over its surface. This tem- 
 perature is about right for galvanizing wrought iron pipe ; 
 the cheaper grades of sheet iron or goods made from it, 
 such as coal hods, ash cans and chamber pails. Heavy 
 malleable iron castings will also coat nicely at this heat. 
 
 For small work, such as nails and. in fact, almost any 
 work that is done in baskets or strung on wires and drawn 
 through a flux, the pyrometer should indicate from 870 
 to 890 degrees of heat. The metal should burn sal 
 ammoniac quickly and oxidize quickly. It will be quite 
 blue in color. This temperature is about right for sheet 
 steel and articles made from it, as well as steel pipe. 
 
GALVANIZING. 29- 
 
 DIPPING THE WORK IN THE MOLTEN METAL. 
 
 We will describe the manner of handling several dif- 
 ferent articles as a general guide for handling all kinds 
 of work. Considerable skill is required to bring a piece 
 of work out of the metal and cool it so that the surface 
 will be smooth, free from blisters and with no lumps of 
 surplus metal attached. 
 
 Before dipping the work, cover the surface of a part 
 of the molten zinc with a flux of sal ammoniac to keep the 
 oxidized metal from adhering to it. To prepare this flux 
 sprinkle a few handfuls of sal ammoniac on the surface of 
 the molten metal, and as soon as it is melted add a few 
 drops of glycerine. This will cause the flux to thicken 
 up and will prevent it. in a measure, from covering the 
 entire surface of the metal. The glycerine also causes 
 the flux to remain stationary, so that when the operator is 
 ready to draw the article from the bath the flux will not 
 cover the space he has cleared with his skimmer for that 
 purpose. The tool designated D in Fig. 13 is used for 
 the purpose of skimming the surface of the metal before 
 drawing the v\-ork from the bath. 
 
 This flux not only prevents the zinc from oxidizing, 
 but it assists the metal to take quickly and evenly to the 
 work. Keep the flux fresh by adding more sal ammoniac 
 from time to time. 
 
 We will suppose the article to be dipped is a cast iron 
 s-ink or some similar casting — that is, a thin casting. 
 Have the metal at the temperature first described under 
 the heading " The Heat of the Zinc." After satisfying 
 himself that the casting is perfectly dry and hot enough to 
 have expelled all moisture from it the operator catches the 
 article with a pair of tongs and plunges it as quickly as 
 possible, and not cause the metal to spatter, into the mol- 
 
3© GALVANIZING AND TINNING. 
 
 ten zinc. He must hold the article beneath the zinc until 
 it is as hot as the zinc itself. After the article has been in 
 the bath a few minutes it should be rinsed around in the 
 metal in such a way that the flux floating on the surface 
 of the molten zinc will come in contact with all parts of it. 
 When the article is thoroughly coated clear a space on the 
 surface of the molten zinc with the skimmer, and after 
 dusting on a very little dry powdered sal ammoniac draw 
 the article from the metal. 
 
 In performing this operation catch the article with 
 the tongs in such a way that the part they grasp will be 
 the last to leave the metal. Do not lift the article clear 
 cf the metal with the tongs you use in the metal, but pro- 
 vide a second pair to handle the article with until it is 
 cooled. In drawing the article raise it slowly with the 
 tongs held in the position described, and as soon as it is 
 partly clear of the metal grasp it with the tongs provided 
 for that purpose, and complete its removal. Hold the 
 article in such a position as will admit of the metal flowing 
 to one point, and just as the drop is about to harden re- 
 move it with a stiff brush or an old file. Expose the ar- 
 ticle to the air until crystals appear, and then brush it 
 vi^ith a brush wet in clear water. Do not dip the article 
 in water, especially if it is a sink or a very thin casting, as 
 that would be quite likely to break it. In any event the 
 coating would not be as bright as it would be if left to cool 
 gradually after brushing with the wet brush. Thick 
 heavy castings may be dipped in water at once on remov- 
 ing them from the molten metal. 
 
 Coal hods and similar goods of sheet steel or iron only 
 require to be left in the bath a few seconds. The flux 
 through which they pass should be confined at one end of 
 the kettle by a piece of sheet iron long enough to go across 
 
GALVANIZING. ;^l 
 
 the kettle from side to side. This is called a " flux guard," 
 and it should enter the metal about 2 inches, with the 
 upper edge as high or a little higher than the sides of the 
 kettle. In galvanizing sheet metal ware the flux should 
 be made to foam up nearly to the top of the kettle by using 
 glycerine. The goods should be passed through this flux 
 into the metal, and as soon as they are coated, which will 
 be in a very few seconds, they must be passed under the 
 flux guard to the end of the kettle that is kept free of flux. 
 In passing the article under the flux guard keep the open- 
 ing up so that none of the flux will be carried along with 
 it. Remove the article from the metal in the way just de- 
 vScribed for sinks and similar articles, but do not sprinkle 
 the surface of the zinc with sal ammoniac. Allow the 
 work to cool in the air. If any particles of the sal am- 
 moniac have adhered to the work in drawing it from the 
 molten metal remove them with a wet brush. 
 
 Some articles can be galvanized very nicely by string- 
 ing them on stout wires about i ^ feet long. When this 
 method is employed string on a number of the pieces, and 
 then bring both ends of the wire together and clinch them 
 securely. To suspend work in the metal strung this way 
 use a hook, shaped after the form given in Fig. 13 and 
 designated C. Provide several of these hooks, so that a 
 batch may always be ready when the previous one is re- 
 moved from the kettle. A piece of ^-^-inch round iron, 
 bent in the shape of the letter S, will serve to remove the 
 strings of castings from the hooks, and also for handling 
 them after they are removed. The wires E and G, Fig. 13, 
 are intended for stringing small articles on for the pur- 
 pose of dipping them in the molten metal. 
 
 In handling small articles on these wires use a motion, 
 after thev are drawn from the metal, calculated to free 
 
32 GALVANIZING AND TINNING. 
 
 them of surplus metal and also to prevent their adhering 
 to each other when they are plunged in the water. To do 
 this properly will require some practice. 
 
 It is a good plan to warm the cooling water slightly 
 for cooling some articles, and to have a thin film of oil on 
 the surface. Small articles strung on wires may be drawn 
 through the metal after sprinkling on a small quantity of 
 powdered sal ammoniac, or may be drawn through a clear 
 thin flux of sal ammoniac, to which a few drops of glycer- 
 ine have been added. If the latter plan is used, as it should 
 be if the articles are such as are liable to rub and stick 
 together, the oil should not be used on the cooling water. 
 
 Small work that cannot be strung on wires may be 
 galvanized by using a basket of wire or sheet iron. We 
 have already described these, and they are designated in 
 Fig. 13 as A and B. 
 
 When these baskets are employed the flux should be 
 of a consistency that will run freely among the work. A 
 block of iron should be placed in a position beside the 
 kettle that will permit the operator to rest the handle of 
 his basket over the block with the basket hanging over 
 the kettle. Using this block as a rest, the operator should 
 shake the basket sharply, and for several seconds, to free 
 the work of surplus metal, and when it is accomplished 
 he will shake them into the water to cool them, after which 
 dry them off by dipping them in boiling water and then 
 throwing them into sawdust. Nails or tacks may be 
 shaken out of the basket onto an iron plate, placed at an 
 angle, over a tub of water. The plate should be inclined 
 sufficient to allow the work to slide into the water readily. 
 
 Sheet iron, wire, wire cloth and poultry netting are 
 mostly passed through the zincing bath mechanically, and 
 as the means employed are too expensive and complicated 
 
GALVANIZING. 
 
 to illustrate or describe we shall not attempt it. Sheet 
 iron may be, and once was. galvanized by parting the ket- 
 tle lengthwise with a tlux guard. The side where the 
 prepared sheet enters the bath is covered with a sal am- 
 moniac flux, and the opposite side, where it leaves the bath, 
 is covered with coke dust to the depth of about i inch.' 
 A light single block and fall is used to assist in drawing 
 the sheet from the kettle, and every kettle in which work 
 of large size is galvanized should be so provided. 
 
 Wire cloth, wire and poultry netting may be galva- 
 nized by running it through the kettle by means of a reel. 
 In galvanizing wire cloth and poultry netting the kettle 
 should be parted by a fiux guard, as previouslv described 
 and the coke dust piled up to a depth of several inches and 
 kept sprmkled with water by using an ordinary watering 
 pot. 1 he flux should be present where the work enters 
 the metal. 
 
 Wire requires no flux at the point where the work 
 enters or on any other part of the kettle. Sand or coke 
 dust or dies of asbestos may be used to wipe off the sur- 
 plus metal. If the kettle for wire is the usual length of 
 10 teet the wire may be drawn through the metal at a 
 speed of about 75 feet per minute. If it is being done in 
 a short kettle the speed must be slow enough to allow the 
 work to be perfectly coated. 
 
 In Fig. 19 we give the position of the different pieces 
 of apparatus required to do the work in a small' way 
 Large plants equipped to do this work exclusivelv are 
 fitted with reels driven by power, and several strands are 
 run through simultaneously. In Fig. 19 A is the position 
 of the reel holding the black wire, B is the tank holding 
 the muriatic acid, C is the kettle, D a tank containing 
 water and E the position of the reel for drawing the wire 
 
GALVANIZING AND TINNING. 
 
 •I 
 
 I 
 
 CO 
 
 I 
 
 o 
 
 
 
GALVANIZING. 
 
 35 
 
 Fig. SO.— Perspective of Dross Kettle. 
 
 Fig. 21.— Top Plan of Dross Kettle. 
 
36 
 
 GALVANIZING AND TINNING. 
 
 THE FORMATION OF DROSS IN THE KETTLE. 
 
 The waste caused by the formation of dross is quite 
 large, even with an experienced man in charge of the ket- 
 
 Fig. ^2— Vertical Section of Fig, 21 at A. A, 
 
 Fig. S3.— Horizontal Section of Fig. 22 at Grate Line. 
 
 tie. The amount of dross made is increased by faihire in 
 keeping the metal at a temperature that will not injure it, 
 by allowing the work to be lost in the kettle and through 
 
GALVANIZING. 
 
 37 
 
 t^^^^^^^^^^^ 
 
 -tAVVXV^V^^,^^^ 
 
 Fig. ^4>— Details of Dross Kettle. 
 
38 GALVANIZING AND TINNING. 
 
 immersing in the kettle work that has not been properly 
 prepared. 
 
 As the dross forms it settles at the bottom of the kettle, 
 and when the accumulation is such that it interferes with 
 the work it must be removed. As the dross settles it be- 
 comes hard, and is easily removed by the proper appliance 
 for that purpose. The tooj for removing the dross is 
 called a " dross scoop." In Fig. 13 we show the shape 
 of this tool, designated F, where a round bottom kettle is 
 in use. The handle of the scoop should be about twice 
 the length of the kettle, unless the kettle is of a size that 
 requires the use of tackle in drossing it. The scoop 
 should be well perforated to allow the clear metal to flow 
 back into the kettle. In removing the dross use care not 
 to stir or rile more than possible when forcing the dross 
 scoop into the hardened mass. Force the scoop into the 
 dross gently, and when you are satisfied that the scoop 
 is full, raise it out of the metal by resting the handle of 
 the scoop on the end of the kettle to get a leverage. Let 
 the scoop remain over the kettle until all the clear metal 
 that will has dripped back into it. If the handle of the 
 scoop is rapped with a hammer or piece of iron it will 
 cause more of the clear metal to separate from the dross 
 than would be the case if it was not done. As soon as 
 the clear metal has ceased to drip dump the dross into cast 
 iron pans. These pans should be about 2 inches deep, 15 
 inches long and 9 inches wide. 
 
 Dross hardens very rapidly when exposed to the air, 
 and no more time than is necessary to allow all the metal 
 possible to drip back into the kettle should be consumed 
 in getting it into the dross pans. 
 
 If there is a large amount of dross in the kettle and it 
 is desired to allow the fi-res to go completely out it should 
 
GALVANIZING. 
 
 39 
 
 be removed. If the kettle is allowed to cool with a large 
 amount of dross lying in the bottom of it the result will 
 most likely be a burst kettle. Before commencing to 
 dross the kettle — that is, remove the dross — skim all the 
 flux from the surface of the metal with a perforated 
 skimmer. This tool is shown in Fig. 13, and is desig- 
 nated H. 
 
 RUNNING OVER OR " SWEATING '' ZINC DROSS. 
 
 The writer is often asked if it pays the galvanizer to 
 try and recover the good metal from the dross, and how 
 best to accomplish it. \\' ithout entering into a discussion 
 regarding the desirability of attempting its recovery, from 
 a financial point of view, we will say that it is our prac- 
 tice to " sweat " our dross. 
 
 In Fig. 20 we give a perspective view of the kettle 
 and brick work for running over dross. Fig. 21 is a top 
 view, Fig. 22 is a vertical section at A A and Fig. 23 is 
 a horizontal section at the grates. The kettle and casting 
 details for bricking in are shown in Fig. 24. The ar- 
 rangement is so simple that we do not think it necessary 
 to describe it in detail. 
 
 The kettle should be made of cast iron, with the bot- 
 tom about I inch thick. A kettle 30 inches in diameter 
 and 20 inches deep answers the purpose very well. 
 
 To separate the good metal from the dross first melt 
 up about 6 or 8 inches of lead in the bottom of the kettle 
 and then put in the dross. Bring the dross to a temper- 
 ature that will cause it to have rather a dark blue color 
 or where the pyrometer will register about 1050 degrees. 
 When this is accomplished stir the mass with a long 
 handled ladle for about one-half hour, and then allow it to 
 settle. When the mass has settled the lead will be at the 
 
40 GALVANIZING AND TINNING. 
 
 bottom, the dross will lie on the lead and the clear metal 
 will be at the top, where it can be bailed out into pans. 
 The stirring may be repeated once or twice after each 
 bailing- operation. After all the clear metal has been ex- 
 tracted that can be remove the dross and put it into pans. 
 
TINNING IRON AND STEEL 
 
 41 
 
TINNING MALLEABLE IRON, 
 
 WROUGHT IRON AND STEEL 
 
 Simply to give articles of malleable and wrought iron 
 a coating of tin is a comparatively easy process to master, 
 but tinning on certain articles of hardware has reached a 
 high state of perfection, and to tin saddlery hardware and 
 the cheaper grades of table cutlery requires considerable 
 skill. The methods employed to do the work vary greatly 
 in different establishments, and the degree of perfection 
 attained is equally at variance. Work that is tinned in an 
 indifferent and slovenly manner is not necessarily done 
 cheaply, as the material wasted on an article roughly and 
 imperfectly coated is of more value than the slight saving 
 in labor cost obtained by rushing the work through without 
 proper attention to obtaining a light and even coating. 
 The high price of the metal used to tin articles makes 
 the cost of the material much more than the labor cost. A 
 loss of TO per cent, of the material by careless handling 
 would represent a much larger proportion of the entire 
 cost of the work than would an increase of the same per 
 cent, added to the labor cost. Painstaking in bringing 
 out the finished article free from surplus tin not only 
 adds greatly to the commercial appearance of the goods, 
 but materially decreases the cost of the work. This eco- 
 nomical result is reached by careful attention to the heat 
 of the tinning bath and to the skillful handling of the 
 articles after their removal from the tinning pot and be- 
 
 43 
 
44 GALVANIZING AND TINNING. 
 
 fore they are cooled. If the tin is not hot enough the 
 articles will be heavily coated, and it will cool on the work 
 l3iinchy and wavy. A degree of heat above a certain 
 limit also causes the work to have a rough and uneven 
 appearance, injures the color and destroys the luster. 
 The use of a good pyrometer in a tinning bath is a great 
 help to the operator in maintaining a uniform heat of the 
 tin. 
 
 PREPARING THE WORK. 
 
 Ordinarily the common grades of tinned articles are 
 made ready for tinning by simply removing the sand, scale 
 or rust by an application of either commercial sulphuric, 
 muriatic or hydrofluoric acid. The finer grades of work 
 are prepared for tinning by careful and lengthy rolling 
 in gravel and water. This preparation not only effect- 
 ually removes all impediments to a perfect coating, but 
 gives the articles a smooth and perfect surface on which 
 to deposit the tin, the degree of perfection obtained being 
 determined by the time and care expended in the rolling 
 operation. 
 
 A piece of wrought iron from which the scale has been 
 removed by the application of acid will not have the 
 smooth and perfect coating that the same would have if 
 the removal of the scale was accomplished by irritation. 
 The same is true of articles of malleable iron. The best 
 and most perfect results are obtained by giving the cast- 
 ings a thorough tumbling in gravel and water, which 
 operation brings the surface of the castings to a state of 
 smoothness only equaled by buffing or grinding. ]Mal- 
 leable castings on which it is desired to obtain a fine fin- 
 ish should invariably be given this treatment. It is, of 
 course, necessary that the patterns from which castings 
 
TINNING. 45 
 
 are taken that are designed to be tinned be made with a 
 view to obtaining- the smoothest surface possible as an 
 assistance to the tumbHng operation. 
 
 Some tinners not only roll their castings in gravel and 
 water, but for the purpose of obtaining a still finer surface 
 than can be obtained by this method they roll them in 
 dr}-, coarse sand, and also give them a third rolling with 
 scraps of leather, the entire operation often requiring 30 
 or 40 hours in going through the several treatments. 
 Water rolling is so conmion and so thoroughly understood 
 that we consider it unnecessary to go into detailed instruc- 
 tions regarding the apparatus to be used or the methods 
 to be employed. There are several concerns who make 
 the manufacture of rolling barrels for this purpose a spe- 
 cialty, and the cheapest method to adopt in equipping a 
 tinning plant with wet rolling barrels would be to buy the 
 outfit from a manufacturer who has made the business a 
 study. 
 
 The care of the tin, in regard to keeping it free from 
 dross or slag, is an important point in obtaining perfect 
 work, and will be referred to in its proper place, 
 
 TOOLS AND KETTLES. 
 
 The tools employed in handling the work are very 
 simple in construction. They consist of w'ires formed 
 into various shapes, perforated ladles or baskets made 
 from sheet iron or wire cloth, and tongs with the jaws 
 formed to adapt themselves to the various articles it is 
 designed to handle with thern. Those illustrated by Fig. 
 13 in chapter on galvanizing will be found useful and all 
 that will be required in many cases. The ingenuity of 
 the operator will readily suggest what is required for the 
 work in hand. 
 
/ 
 
 46 GALVANIZING AND TINNING. 
 
 The number of tinning kettles to be used depends alto- 
 gether on the class of goods to be tinned. The most com- 
 mon kinds of hardware specialties can be tinned very sat- 
 isfactorily by the use of a single kettle of tin, while the 
 better class of tinning, such as saddlery hardware, iron 
 spoons, etc., require, in order to get the best results, two 
 kettles, and three may be employed to good advantage. 
 
 Where a plant is fitted up to do a fine grade of tinning 
 the kettle used to give the castings their first coating of 
 tin is designated as the " roughing kettle." and the other 
 kettle or kettles as the finishing. When the roughing ket- 
 tle is used no particular care is necessary to have the ar- 
 ticles come out smoothly coated or free from surplus tin, 
 as the unevenness of the coating will be removed by their 
 later treatment in finishing. The object of the roughing 
 kettle is to give the iron a thorough coating of tin as 
 rapidly as it is prepared to receive it, which prevents rust- 
 ing. After the iron receives a thorough coating of tin it 
 may be stored away until it is desired to finish it. 
 
 For those having only a small amount of tinning to 
 do it would not pay to invest in an expensive outfit of wet 
 rolling barrels, and very good results can be obtained 
 without them. We will say here that only a few of the 
 large concerns engaged in tinning are so fitted and the 
 work they turn out is of a nature that calls for the best 
 results possible to obtain as regards smoothness and 
 brightness of the finished work. 
 
 A TINNING PLANT. 
 
 In installing a tinning plant the convenient handling 
 of the work should be given all the consideration possible, 
 and the operator will find it a great help toward making 
 his work easy, as well as to the advantage of his employer. 
 
TINNING. 47 
 
 if he will make a study of the best methods and tools to 
 employ in handling the various articles that come to him 
 to be tinned. 
 
 While it is our purpose to treat this subject in a man- 
 ner that will enable a novice to make a successful begin- 
 ning, the best results can, of course, only be reached by 
 actual practice. With the principles and requisites nec- 
 essary to perfection in results obtained well understood, 
 there should be no trouble experienced by one of average 
 mechanical ability in mastering the business. 
 
 To make the different operations of preparing and tin- 
 ning articles of malleable iron, wrought iron and steel 
 easily understood, we shall treat each operation separately. 
 
 While the illustrations we give will serve as a general 
 guide in equipping a plant, it does not follow that they 
 must not or cannot be changed to suit local conditions. 
 It would be impossible to illustrate the exact course to be 
 followed in individual cases, and those undertaking the in- 
 stallation of a plant must be governed to a great extent 
 by their requirements as they see them. 
 
 It should be kept in mind in deciding what part of the 
 factory can best be devoted to the tinning department 
 that more or less gases and fumes prevail when the work 
 is carried on. These gases and fumes are not only dis- 
 agreeable to inhale, but are destructive to fine machinery 
 and tools and to finished work. To the end that the work 
 may not become a source of annoyance to those not im- 
 mediately engaged in it and detrimental to machinery and 
 goods, the plant should be located if possible in a build- 
 ing by itself, taking good care to provide good ventilation 
 and drainage. 
 
 A room devoted to this work should not be less than 
 10 feet in hight, and the kettles and acid tanks provide'l 
 
48 GALVANIZING AND TINNING. 
 
 with hoods connected with the ventilators to carry off the 
 gases. The hoods should, of course, be high enough not 
 to interfere with the perfectly free movements of the 
 operator. 
 
 The illustrations given contemplate tanks of cypress 
 or pine for containing the different solutions used in pre- 
 paring and finishing the work, but oil barrels sawed in 
 half may be employed for the purpose if they arc properly 
 cleaned either by burning out the interior or washing in 
 a hot, strong solution of soda ash and water. 
 
 For heating the tin hard coal is best, as it gives the 
 most even heat and is most easily controlled. Soft coal, 
 coke, natural gas and even wood can, however, be em- 
 ployed for the purpose. 
 
 PLAN OF TINNING PLANT. 
 
 We show in Fig. 25 a ground plan for a tinning 
 plant for general work, except the -tinning of common 
 cast iron. In this illustration A denotes the roughing 
 kettle — that is. the kettle containing the tin used to give 
 the work its first coating of tin ; B is the finishing kettle ; 
 C is the tank containing muriate of zinc ; D is what is 
 termed in the trade the " whipping box," which is simply 
 an arrangement to prevent the drops of molten tin being 
 thrown promiscuously over the room when the operator 
 is shaking or swinging his work to free it from the sur- 
 plus metal ; E is a tank made of sheet iron for containing 
 the kerosene oil used in cooling the work, the intent being 
 to have this tank surrounded by running water to keep 
 the oil cool, the water being contained in the companion 
 tank F ; G is a tank provided with a steam coil, the intent 
 being to have the tank filled with clean hot water, in which 
 to rinse the finished work before drying it off in the saw- 
 
TINNING. 
 
 49 
 
50 GALVANIZING AND TINNING. 
 
 dust, which is contained in the box H ; I and O are water 
 tanks used for storing the work after it has been treated 
 in the acid ; K is a tank containing muriatic or sulphuric 
 acid; L and M are acid tanks, the use of which will be 
 explained in the proper place ; N is a tank for containing 
 an alkali solution, and it should be provided with a steam 
 coil ; R R denotes a drain through the center of the room 
 to carry off the waste water. A .sectional plan of this 
 floor is given in Fig. 38. 
 
 REMOVING SCALE AND RUST WITH SULPHURIC ACID. 
 
 To enable -steel and wrought iron to take a coating of 
 tin, the scale and rust must be removed. This is best ac- 
 complished with a pickle composed of 1 part sulphuric 
 acid to about 30 to 40 of water, bringing the solution to a 
 temperature of about 150 degree F. 
 
 If the articles are of such a shape that they pack 
 closely together they must be stirred so that the acid will 
 have free action on all parts alike, otherwise the scale or 
 rust will not be affected on that part that is in contact with 
 another piece, the result being that the acid \Vill burn the 
 material first made clean before the scale is removed from 
 the part in contact. 
 
 In pickling sheets they must be placed in racks that 
 will prevent one sheet lying against another. Sheets 
 should be carefully inspected, and any spots that the acid 
 has not touched must be removed with the aid of a sharp 
 pointed steel. The shank of an old file ground to a point 
 and hardened answers the purpose very well. 
 
 If the articles are small, and it is desired to give them 
 a fine surface, roll them in sand and water after remov- 
 ing the scale and rust with the acid solution, and to fur- 
 ther improve their surface give them a second rolling in 
 
TINNING. 51 
 
 scraps of leather. The effect of roUing is to give the 
 articles a smooth surface, and the smoother the surface 
 obtained the smoother and brighter will be the goods after 
 tinning. 
 
 We do not wish it to be understood that the rolling 
 operation is absolutely necessary to obtain a complete 
 coating of the goods, as they will take the tin perfectly if 
 that operation is omitted, but the appearance of the goods 
 is greatly improved by the rolling, and when it is desired 
 to obtain the best finish possible the rolling barrel must 
 be employed. 
 
 When the removal of scale and rust has been affected 
 and the material is perfectly clean it should be stored in 
 tanks containing clear water, there to remain until the 
 operator is ready to put it through the subsequent opera- 
 tions. Do not allow the work to remain in running water, 
 as it will soon rust or oxidize if it is. 
 
 The operator must not fail to examine the work fre- 
 quently while it remains in the hot pickle to determme 
 when the desired result has been obtained. If it is al- 
 lowed to remain too long a time after the scale and rust 
 have been removed the acid will attack the surface of the 
 material and leave it rough and seamed. Imperfections 
 caused by overpickling cannot be covered up by the coat- 
 ing of tin, and the commercial appearance of the goods is 
 injured. 
 
 The removal of scale and rust can be accomplished by a 
 pickle composed of i part muriatic acid to 15 to 20 parts 
 of water, but the cost is greater and the result obtained no 
 better. It is not advisable to use this acid for the 
 purpose unless the amount of work to be treated is very 
 limited. 
 
 In Fig. 25 K represents the tank to be used for the 
 
52 GALVANIZING AND TINNING. 
 
 purpose just explained, and I indicates the storage tank 
 for the prepared work. 
 
 CLEANING SANDY CASTINGS BY SULPHURIC ACID. 
 
 Castings that have sand on them must be subjected to 
 a treatment that will effectually remove it, as a perfect 
 coating cannot be obtained if a particle of sand remains. 
 The removal of sand can be accomplished by placing the 
 castings on an inclined platform and keeping them wet 
 with a pickle composed of i part sulphuric acid to 6 of 
 water, until the sand is loosened enough to wash off by 
 the application of water. From lo to 20 hours is re- 
 quired to accomplish its removal and then a casting brush 
 often has to be employed to get out all the little particles 
 that are burned in where there are sharp angles. 
 
 Rolling with plenty of sharp scratches or shot is the 
 only sure way to obtain a perfectly clean casting, and we 
 should never attempt to tin malleable castings in any con- 
 siderable quantity without the aid of a rolling barrel. As 
 in the case with articles of steel or wrought iron, the wet 
 rolling barrel supplemented by the dry rolling in leather 
 scraps fits the castings to take a beautiful coating of tin 
 and a bright luster. 
 
 The platform on which the castings are placed for 
 pickling should have a tank placed under one end at its 
 lowest point to catch the acid as it flows from the castings 
 after each bailing operation. This pickling arrangement 
 is designated as L in Fig. 25, and the tank designated as 
 M can be used to store the prepared work until it is de- 
 sired to give it the finishing treatments. 
 
 CLEANING SANDY CASTINGS WITH HYDROFLUORIC ACID. 
 
 We have given the course to be followed for cleaning 
 sandy castings with sulphuric acid, because it may not al- 
 
TINNING. 53 
 
 ways be possible to obtain hydrofluoric acid, and because 
 hydrofluoric acid is a comparatively new agent in the 
 business. Where it is possible to substitute this powerful 
 acid for sulphuric acid it should be employed, as its effects 
 are much more rapid and certain, and are less destructive 
 to the castings. 
 
 In employing hydrofluoric acid to remove sand make 
 a solution for slow pickling in the proportion of i part 
 acid to 30 of water. For quick pickling make the pro- 
 portion I of acid to 20 of water. Immerse the castings 
 until the sand is dissolved, which will be in from 15 min- 
 utes to 3 hours, depending on the strength of the solu- 
 tion and the tenaciousness of the sand. 
 
 A good arrangement for doing this work is to have 
 two tanks, one elevated by means of a bench or stand, so 
 that the bottom of the upper tank will be a few inches 
 above the top of the lower tank. Provide a hole in the 
 upper tank so that when the plug is removed the solu- 
 tion will escape into the lower tank and leave the castings 
 uncovered by the solution. When all the solution has es- 
 caped into the lower tank cover the castings with water 
 until it is desired to remove them for subsequent treat- 
 ments. The solution in the lower tank is ready to use on 
 a fresh batch of castings. We do not show this arrange- 
 ment in Fig. 25, as it can take the place of the sulphuric 
 acid, designated as ]M in that illustration. 
 
 REMOVING PAINT OR GREASE. 
 
 If the work is greasy or has paint on it, it must be 
 cleaned with a hot solution of caustic soda or soda ash 
 and water. Make the solution very hot and strong, and 
 immerse the work in it until it is free from all such mat- 
 ter, after which rinse it thoroughly in clean water. This 
 
54 GALVANIZING AND TINNING. 
 
 Operation should precede pickling when it is necessary to 
 perform it. The tanks for this purpose are designated in 
 Fig. 25 as N and O. 
 
 TINNING WITH A SINGLE KETTLE OF TIN. 
 
 As already stated, very good results can be obtained by 
 simply using one kettle of tin where the commercial ap- 
 pearance of the work is of secondary importance. Where 
 only a single kettle is employed the tin should be main- 
 tained at a temperature of about 500 degrees F., and the 
 work may be cooled in hot water and dried off in saw- 
 dust. 
 
 The operations preliminary to dipping the work in the 
 tinning bath are precisely what they would be if more 
 than one kettle of tin was used. As these operations will 
 be explained in connection with those for using two ket- 
 tles we will not give them here. 
 
 Where only a single kettle is employed more or less 
 trouble will be experienced in keeping the dross or slag 
 which rises to the surface of the tin from adhering to the 
 work and in keeping the tin at a uniform temperature. 
 The dross or slag must be removed from the tin fre- 
 quently with a perforated skimmer, and when the black 
 flux that forms on the surface of the tin from the muriate 
 of zinc, in which the castings are dipped previous to im- 
 mersing them in the molten tin, is present in sufficient 
 quantities to interfere with drawing the work, it must 
 also be removed in part. A small amount is beneficial to 
 the work, but when it accumulates in a sufficient quantity 
 to catch on the work as it is drawn out it is apt to stain 
 the work and leave white streaks wherever it touches. 
 The cooling water should also be kept clean and free from 
 acid. If it is not the work is liable to rust. In Figs. 29, 
 
TINNING. 55 
 
 30 and 31 'we show manner of bricking in a single kettle, 
 the casting details being shown in Fig. 32. 
 
 TINNING WITH TWO OR MORE KETTLES OF TIN. 
 
 When the work has been made perfectly clean from 
 sand, scale, rnst, grease or paint by some one of the treat- 
 ments described, it is ready for the final operations. If 
 the work is of a kind that will admit of its being strung on 
 wires, use such wires as seem best adapted to the work 
 in hand. For many kinds of work a piece of wire bent in 
 the shape of a croquet wicket will be found just the thing. 
 Good stifif wires should be used, and they should be long 
 enough to allow plenty of room for the operator to grasp 
 the ends without getting burned. That is to say, if you 
 have 10 inches of tin in the kettle, make the wire 20 inches 
 long, which will allow 10 inches of wire to be out of the 
 tin where the operator can grasp it when he is ready to 
 draw the work from the kettle. Provide plenty of these 
 wires so that the handling of the work may be facilitated. 
 
 String on wires as much of the work as you think you 
 can handle comfortably, and put them, several strings at a 
 time, into the alkali solution. The work may be allowed 
 to remain in this solution for several minutes, or while the 
 operator is filling more wires. From the alkali solution 
 the work is to be passed into the rinsing tank, and care 
 should be taken that all traces of the alkali are removed. 
 
 When this is accomplished the work is to be given a 
 few minutes' immersion in a solution of muriatic acid and 
 water. This mixture should be in the proportion of i 
 of acid to 4 or 5 of water in cold weather, while in warm 
 weather 8 or 10 of water to i of acid will do the required 
 work. The object of this dip is to remove any trace of 
 rust that may have formed on the work. The tank for 
 
56 GALVANIZING AND TINNING. 
 
 this purpose is designated as K in Fig. 25, and for many 
 kinds of work, such as castings that have been cleaned by 
 dry rolling and goods that have been made of material that 
 has no scale on it, all that is necessary is to give it a few 
 minutes' immersion in this solution. 
 
 From this last dip of muriatic acid and water, which 
 by the way should never be omitted, the work is to be 
 dipped in muriate of zinc, which is the last dip previous to 
 immersing it in the molten tin. Tank C, Fig. 25, is 
 used to contain the muriate of zinc, which solution is made 
 by dissolving scraps of zinc in clear muriatic acid. 
 
 PASSING THE WORK THROUGH THE TINNING KETTLES. 
 
 If two kettles of tin are in use, as shown in Fig. 25 by 
 A and B, take a wire full of the work to be dipped and im- 
 merse it while wet with the muriate of zinc in the kettle 
 of tin designed to give the work its first coating. This is 
 the roughing kettle, and is designated in Fig. 25 as A. 
 Put several of the strings of work into the kettle and 
 allow them to remain until the work is as hot as the tin. 
 The tin in this kettle should be maintained at a heat of 
 about 500 degrees F. 
 
 After the work has remained in the first kettle the 
 requisite time take a wire full in the left hand, and with 
 a skimmer held in the right hand clear a space on the sur- 
 face of the tin large enough to admit of the wire full of 
 work being removed without any of the slag or flux ad- 
 hering to it. Remove the wire full of work and pass it 
 directly to the second kettle. It is not necessary to shake 
 off the surplus tin when removing from the first kettle, 
 but it is necessary to use care that none of the flux or slag 
 is carried over to the second kettle on the work. 
 
 Retaining hold of the wire containing the work the 
 
TINNING. 
 
 57 
 
 Operator allows it to remain in the second kettle for the 
 fraction of a minute until the heat of the work attained in 
 the first kettle is reduced to about the temperature of the 
 tin in the second kettle, which for most purposes should be 
 about 400 degrees F. \^ery small articles may require that 
 the tin in the second kettle attain a temperature of 450 
 degrees F. A much higher heat will cause the tallow, 
 which is on the second kettle, to a depth of >4 to i inch, to 
 ignite. When the work is in the condition named draw 
 it quickly from the tin, and after a few rapid swinging 
 motions to free it of surplus metal plunge it into a tank 
 of kerosene oil, using a motion calculated to keep the ar- 
 ticles from sticking together. A little practice will soon 
 determine what motion is best adapted to keep the ar- 
 ticles separated and also prevent any lumps of tin form- 
 ing on the work. 
 
 D in Fig. 25 denotes the position of the box provided 
 to catch the drops of tin that are thrown from the work 
 as the operator swings it to and fro. E denotes the tank 
 for containing the oil used for cooling, as already ex- 
 plained. The tank containing this oil should be sur- 
 rounded by water to prevent the oil heating to a point 
 where it would ignite. 
 
 The work should be allowed to remain in the oil long 
 enough to set the tin, and it should then be thrown into 
 fine sawdust to clean it of the oil. If the articles are very 
 heavy it may be necessary to plunge them into cold water 
 from the oil. 
 
 Tf the work cannot be strung on wires a " basket " may 
 be used for dipping it. The basket may be of sheet iron, 
 in which case it should be provided with plenty of holes 
 to show the tin to pass off. or it may be made of wire net- 
 ting with a mesh sufficiently small to prevent the work 
 
58 GALVANIZING AND TINNING. 
 
 falling through. Fig. 13 illustrates the shape of these 
 baskets, which are designated as A and B. Nails, tacks, 
 rivets and all similar articles are dipped in the tin by 
 means of these baskets. Tongs are also used for handling 
 heavy articles, but those used in the tin should not be used 
 for cooling the work, as they would mark it. The tongs 
 used for cooling should not be put into the molten tin. 
 Their shape may be varied to suit the form of the article 
 handled. 
 
 TINNING WIRE IN COILS. 
 
 In large manufacturing establishments machinery is 
 employed whereby several strands of wire are passed 
 through the tinning kettle simultaneously. To do the 
 work on a small scale, provide reels that will accommo- 
 date a coil of wire. Place one of the reels in a position 
 where the black wire will pass, as it is uncoiled, through 
 a tank containing muriate of zinc, and then through the 
 kettle of tin. The other reel is placed in a position where 
 it will take up the wire as it passes through the tin. The 
 reel used to draw the work through the kettle must, of 
 course, be provided with an arrangement for turning it, 
 and a device to hold the wire under the muriate of zinc 
 and also under the tin as it passes from one reel to the 
 other must be employed. As the necessary arrangement 
 will readily suggest itself we do not think it necessary to 
 illustrate it. 
 
 At the point where the wire leaves the molten tin a 
 piece of tow is twisted around the strand, sufficiently 
 tight to wipe off the surplus metal, which flows back into 
 the kettle. If the wire is very heavy it must be made to 
 pass through water after it leaves the tin, the water tank 
 being placed where the wire will not enter it until it has 
 
TINNING. 
 
 59 
 
 passed through the bunch of tow used to wipe off the 
 surpkis metal. 
 
 If the wire is covered with a heavy scale or rust it 
 must be cleaned in sulphuric acid the same as any other 
 work. If it is bri,e:ht wire all that is necessary is to im- 
 merse it in a solution of muriatic acid and water, i part 
 acid to 6 of water. If wire is to be tinned in quantity a 
 long shallow kettle is best adapted to the purpose. 
 
 TINNING STEEL SPOONS AND SIMILAR ARTICLES. 
 
 For this purpose provide a good sized kettle for 
 " roughing " the work — that is, for giving it a prepar- 
 atory coating. For finishing the work use small kettles. 
 A kettle 15 inches long, 8 inches wide and 6 inches deep 
 is ample for work of this kind. We refer to a plant fitted 
 especially for this business. The work can be done in an 
 outfit such as we illustrate by Fig. 25, but large finishing 
 kettles are not as well adapted for this business as small 
 ones, as the tin in a large kettle is apt to become dull in 
 color by constant use, while in a small kettle the tin is 
 turned over more rapidly, which allows it to hold its color 
 much better. 
 
 The articles should be rolled in tumbling barrels 
 with scraps of leather and then carefully cleaned in 
 an alkali solution. After rinsing off the alkali they should 
 be immersed in quite a strong solution of muriatic acid 
 and water for five or ten minutes, and then dipped in the 
 roughing kettle by means of a wire basket, first dipping 
 the work in a solution of muriate of zinc. As soon as 
 they are thoroughly coated shake them out of the basket 
 in such a way as will insure the separation of as many as 
 possible. It makes no difference whether thev come 
 
So GALVANIZING AND TINNING. 
 
 smooth or not so long as they are thoroughly coated. 
 The smoothness will come in the finishing operation. 
 
 To finish the goods take them, a piece at a time, in a 
 pair of tongs adapted to hold them and immerse in the 
 finishing kettle, the tin in which is covered with beef tal- 
 low to the depth of about ^ inch. As soon as the article 
 reaches the same heat as the tin remove it and allow it to 
 cool enough so that the tin will not run, after which wipe 
 up the goods in flour. 
 
 RETINNING. 
 
 This branch of the business is comparatively simple, 
 since no pickling is required. An outfit for doing the 
 work usually consists of the three kettles — one for rough- 
 ing the work and two for finishing. The roughing ket- 
 tle is usually set up by itself, although it may be con- 
 tained in the same brick work with the finishing kettles. 
 
 For retinning, kettles shaped like those used for sweat- 
 ing zinc dross are best adapted for the work, and the man- 
 ner of setting is practically the same. They should be 
 co\'ered with a hood to catch the smoke and fumes which 
 are constantly rising. The hood should be constructed 
 to leave one side open so that the operator has free access 
 to the kettles from one side. A view of a " tinning stack " 
 resembles an open grate or the fire place of olden times, 
 the brick setting to the kettles being about the hight of an 
 ordinary work bench. 
 
 The finishing kettles are kept covered with beef tal- 
 low and palm oil, and care must be taken to prevent any 
 dross or slag being carried over from one kettle to the 
 other in the operation of passing the work from kettle to 
 kettle. When large articles are being treated, like pressed 
 
TINNING. 
 
 61 
 
 dishpans, a swab of hemp is often used to free the article 
 from dross before removing it to the last kettle. 
 
 In drawing the article from the finishing kettle the 
 
 Fig. 26.— End Elevation of Brick Work for Setting Two Kettles, 
 
 Fig. 27.— Vertical Section through Fig. 26 at A\ A\ 
 
 motion should not be too rapid. The piece should be held 
 in one position and the drop of tin that forms at the low- 
 est point removed by passing a piece of round iron along 
 
62 
 
 GALVAXIZTNG AND TINNING. 
 
 the edge. One end of this rod of iron is kept in the kettle 
 of tin so that it is always ready for use. 
 
 When the tin has " set," the article is passed to the 
 
 Fig. S8. ^Horizontal Section through Fig. S6 at B\ B\ 
 
 Fig. 29.— End Elevation of Brick Work for Setting Single 
 
 Kettle. 
 
 " bench " to be rubbed in flour. In large establishments 
 girls arc mostly employed to clean the work with flour 
 after it is tinned. 
 
TINNING. 
 
 63 
 
 The heat of the tin must be gauged to a nicety. If 
 too hot the tallow will ignite and the work come out yel- 
 low. If too cool the coating will be heavy and will not 
 flow smoothly. 
 
 It is perhaps unnecessary to say that in case rust has 
 
 Fig. SO.— Section through Fig. 29 at A\ A\ 
 
 Fig. 31.— Section of Fig. 29 at B\ B\ 
 
 formed on the work from any cause it must be removed 
 with acid the same as from any other work. Preparatory 
 to dipping in the roughing kettle the work must be dipped 
 in muriate of zinc. 
 
64 
 
 iALVANIZING AND TINNING. 
 
 SETTING RETINNING KETTLES. 
 
 Kettles for retinning are set in a variety of ways, and 
 hardly any two plants have the same arrangement of kettles 
 or other apparatus. The principal point to consider in 
 
 
 B 
 
 
 
 
 
 
 
 
 
 "XS" 
 
 D^ 
 
 Fig. S2. — Details of Tinning Kettle. 
 
 bricking in kettles for retinning and, in fact, those for any 
 purpose, is to place the fire and ash pit doors where thev 
 will not interfere with the working of the kettles while the 
 fires are being attended to. 
 
TINNIxVG. 65 
 
 We give in Figs. 39 and 40 perspective views of the 
 brick setting of a retinning stack. Fig. 39 shows the ket- 
 tles in position, and Fig. 40 is a view of the back of the 
 stack, showing the fire and ash pit openings. 
 
 In these illustrations the entire stack is represented as 
 being of brick. This plan is undoubtedly the most eco- 
 nomical in the end, although many stacks are inclosed 
 with sheet iron about the brick work surrounding the 
 kettles. We think the perspective views will enable one 
 to construct a stack without our giving the entire arrange- 
 ment in detail, as we do in Figs. 26 to 31, inclusive. 
 
 Fig. ^2 shows the casting details for setting kettles as 
 represented by Figs. 26 to 31, inclusive. A gives a 
 top, side and end view of the kettle ; B shows the coping 
 plate : C is the grate in detail ; D is the front bearing bar 
 in detail, and E the back bearing bar. The position of 
 each piece is designated by a corresponding letter in Figs. 
 26 to 31, inclusive. 
 
 Fig. 26 is an end elevation of the brick work, Fig. 2y 
 is a vertical section of Fig. 26 at A' A' and Fig. 28 is a 
 horizontal section of Fig. 26 at B' B'. Figs. 29, 30 and 
 31 show the manner of bricking in a single kettle. 
 
TINNING COMMON GRAY IRON. 
 
 The tinning of common gray iron castings has become 
 quite an extensive industry in the last seven or eight years. 
 Previous to this time there were only one or two parties in 
 the country able to do the work with any degree of suc- 
 cess. While manufacturers had long recognized the fact 
 that tin was a much more desirable metal tlian zinc for 
 coating certain articles of culinary use the want of a cheap 
 and practical process for tinning on gray iron precluded 
 their giving the matter serious attention. 
 
 The author perfected a method in 1891. a full descrip- 
 tion of which will be given in this article, that proved a 
 practical success, and to-day it is almost impossible to sell 
 zinc coated articles that are to be used in the preparation 
 of food. 
 
 In addition to the uses to which tinned gray iron is 
 put by the manufacturers of kitchen and other hardware 
 specialties, it has been found of great advantage to give 
 articles of cast iron that are to be copper or brass plated a 
 coating of tin previous to plating them. The advantages 
 come from the lessened quantity of material necessary to 
 use in electroplating, the preventing of " leaking " or 
 '' sweating," so common where the plating is deposited 
 directly on the bare casting, and also in giving the articles 
 the appearance of spelter or brass castings. 
 
 By this process gray iron castings are prepared for 
 tinning by rolling them in a solution of muriatic acid, sal 
 ammoniac and water, the rolling barrel being constructed 
 
 60 
 
TINNING. 67 
 
 to retain at a high pressure the gas formed by the chem- 
 icals used. The use of this barrel makes it desirable to 
 locate the tinning plant in a building by itself, as the gas 
 generated is constantly escaping, carrying with it quan- 
 tities of the solution. At the best the barrel room for 
 gray iron tinning is a wet, dirty place, and the entire op- 
 eration requires the use of considerable water. 
 
 DESCRIPTION OF TINNING PLANT. 
 
 In erecting a building for this purpose particular atten- 
 tion should be paid to ventilation and drainage. A plan 
 for constructing a floor, with a view to perfect drainage, 
 is shown by Fig. 38. The arrangement of the outfit is 
 shown by Fig. 33, in which A is the rolling barrel for pre- 
 paring the castings for tinning. B is a tank to receive the 
 castings after they have been treated in the rolling barrel 
 A. This tank should be provided with trucks, and a 
 track should be laid so that the tank can be run under the 
 rolling barrel to receive the prepared work. C is a tank 
 for storing the prepared castings previous to further treat- 
 ment, as hereafter described ; D,E, F and G are divisions of 
 one common tank ; D is to contain an alkali solution, and 
 is to be provided with a steam coil, as shown, to heat the 
 solution ; E is a compartment for containing water for 
 rinsing; F is to contain an acid solution; G is for the 
 muriate of zinc ; H is the roughing kettle of tin ; K is the 
 finishing kettle ; L is the oil for cooling the work. The 
 arrangement of this tanR was explained in the chapter on 
 general tinning ; M is a wooden tank large enough to ac- 
 commodate the iron tank L and allow it to be surrounded 
 with water ; N is a tank for containing hot water, in which 
 the tinned work is dipped to remove any traces of oil or 
 acid; it is provided with a steam coil, as shown; O is a 
 
68 
 
 GALVANIZING AND TINNING. 
 3r 
 
 8 
 
 I 
 
 CO 
 
 Si 
 
 •2. 
 
 s 
 
 
 o 
 C5 
 
 
TINNING. 69 
 
 box to contain sawdust for drying off the work when 
 it comes from the hot water contained in the tank N ; R R 
 is a drain for carrying oft the waste water and S S are 
 the tracks for moving the tanks B and C ; T is a tank for 
 containing a sohition of hydrofluoric acid, to be used as 
 hereafter described, and U is a storage tank. It is per- 
 haps needless to say that the ground plan may be changed 
 to suit local conditions. 
 
 Only the most simple tools are required, which may 
 be varied by the ingenuity of the operator to suit existing 
 conditions of work. We give a sketch showing the most 
 common in Fig. 13. 
 
 GENERAL CONSIDERATIONS. 
 
 In preparing gray iron castings to take a coating of 
 tin there are several essential things to be taken into con- 
 sideration : the quality of the iron, the form of the cast- 
 ings, their condition when they come to the tinner, and if 
 cored, the nature of the cores used. 
 
 Hard iron needs a longer preparation than soft iron 
 and a longer immersion in the molten tin. Castings that 
 are made from patterns not designed with a view to avoid- 
 ing sharp angles, in which the molding sand can find lodg- 
 ment, are much more difficult to prepare than those made 
 from patterns free from these obstacles. It is, of course, 
 not always possible to do away with sharp angles in mak- 
 ing patterns for castings that are designed to be tinned, 
 but whenever possible they should be avoided in the inter- 
 est of easy cleaning from sand and perfect coating of the 
 w^ork. 
 
 Castings that have been freed from sand by the use of 
 sulphuric acid require a special preparation before they 
 will take a perfect coating of tin, and the use of this acid 
 
70 
 
 GALVANIZING AND TINNING. 
 
 should be avoided if possible. Cored castings made with 
 cores in which rosin has been used must be treated dif- 
 ferently from those made with an oil or glue core. For 
 the intelligent understanding of the different conditions 
 we give the specific course to be followed in each case. 
 
 Fig. Slf,. — Top View of Rolling Barrel with Receiving Tank 
 
 in Position. 
 
 The perfect coating of gray iron requires the use of 
 two tinning kettles, and where castings are to be tinned 
 previous to electroplating three kettles of tin should be 
 used to insure .the smoothest coating and the brightest 
 luster. 
 
 TUMBLING BARREL. 
 
 An outfit for preparing and tmning cast iron consists 
 of a tumblintr barrel, constructed in accordance with the 
 
TINNING. 
 
 71 
 
 plan shown by Figs. 34, 35, 36 and 2,7- The points 
 whereni this barrel differs from the ordinary wet rollino- 
 
 Fig. SS.Side View of Fig. 34, 
 
 —J -^'^ T 
 
 Fig. S6.—Gear End of Fig. S4. 
 
 barrel are that it is built very heavy and strong-. It is 
 provided with valves for the escape of the gases generated 
 
72 GALVANIZING AND TINNING. 
 
 by the chemicals used, and the opening where the barrel is 
 filled is arranged to close tightly. 
 
 For general work we prefer a barrel 48 inches long 
 and 24 inches in diameter. The shell we make of ^-inch 
 boiler iron, and use cast iron heads iVz inches thick. The 
 manhole cover we make i inch thick, and have it well 
 ribbed to give additional strength. 
 
 Fig. 34 is a top view of the barrel, and it also shows 
 the receiving tank H, designated in the ground plan, Fig. 
 33, as B. 
 
 Fig. 35 is a side view of Fig. 34, and Fig. 36 is a view 
 of the gear end of the barrel. 
 
 Fig. 37 gives the details of the barrel, in which A is an 
 end view of the trunnions B, and C and D are the pillow 
 blocks supporting the barrel and E those for the pinion 
 shaft ; F is the valve for the relief of gas and G is a view 
 of the end of the barrel on which the valves F are placed. 
 
 Two or more kettles (depending on the nature of the 
 work) set after the plan illustrated by Figs. 26, 27 and 28, 
 and various tanks built after Fig. 12, complete the outfit. 
 
 The first operation in preparing the castings for tin- 
 ning is to free them from sand. This is best accomplished 
 by the use of the ordinary tumbling barrel, which gives 
 the castings a smooth clean surface while doing the work 
 of removing the sand. Where the castings are of a na- 
 ture to prevent their perfect cleaning by tumbling, the 
 sand should be removed by a solution of hydrofluoric acid 
 and water. Sulphuric acid will do the work, but in a 
 much inferior manner and to the injury of the castings in 
 relation to their ready and perfect coating. The reason 
 for this is easily understood. Hydrofluoric acid acts di- 
 rectly on the sand, dissolving it rapidly without attacking 
 the iron to any great extent. The action of sulphuric acid 
 
TINNING. 
 
 n 
 
 1 .^ 
 
 ?q r 1 
 
 
 
 
 O |l 
 li 
 
 0) 
 
 D 
 
 r^,' ' 
 
 m ;;^ 
 
 
 Fig. 37.— Details of Rolling Barrel 
 
74 
 
 GALVANIZING AND TINNING. 
 
 is the reverse, the iron being dissolved on the surface, 
 causing the sand to fall oft", while the sand itself is not 
 affected. 
 
 FREEING GRAY IRON CASTINGS FROM SAND BY HYDRO- 
 FLUORIC ACID. 
 
 While this operation is nearly the same as the one 
 given for cleaning malleable iron by the use of this acid 
 
 
 Fig. SS. — Detail of Floor Drainage. 
 
 we wish to impress the operator with the fact that in 
 treating gray iron with acid of any kind, for the purpose 
 of preparing it for tinning, much more care must be ex- 
 pended in the operation than with malleable iron, as the 
 overpickling of gray iron leaves the surface soft and 
 gummy, in which condition it will not take a coating of 
 tin, and it is no easy matter to get it in a condition where 
 it will. 
 
 For quick cleaning of sandy castings by the use of 
 hydrofluoric acid the preparation should be i of acid to 
 
TINNING. 
 
 75 
 
 Fig. 39.— Front View of Retinning Stack. 
 
 Fig. 40.— Back and End Vieiv of Fig. 39. 
 
76 GALVANIZING AND TINNING. 
 
 20 of water. For slow cleaning, which ir necessary on 
 castings having sharp angles into w^hich the molding sand 
 has burned, use the acid in the proportion of i of acid to 
 30 of water. The castings may remain in this solution 
 until the sand is dissolved, after which, provided they 
 have not been made with rosin cores, they are ready to be 
 placed in the tumbling barrel used to prepare them for 
 tinning. If rosin cores have been used they are to be 
 treated in a special way, which will be explained in its 
 turn. 
 
 A good arrangement to clean sandy castings with 
 hydrofluoric acid is to have two tanks (oil barrels sawed 
 in half will answer), one elevated above the other by 
 means of a stand or bench, so that the top of the lower 
 tank will be 3 or 4 inches below the bottom of the ele- 
 vated tank. Bore a hole in the side of the upper tank 
 close to the bottom and provide a plug. Place the cast- 
 ings in the upper tank and cover them with the solution, 
 which has previously been mixed and is contained in the 
 tank below. When the castings have been completely 
 freed from sand remove the plug and allow the solution to 
 escape into the tank below, where it remains until re- 
 quired for use again. No specific rule can be given as to 
 the time required to clean the castings, and it is not neces- 
 sary, as an examination of the work from time to time 
 while under treatment will determine when they are clean. 
 Castings on which a light sand is attached might be clean 
 after 15 minutes' immersion in the solution, while castings 
 having a heavy coating of sand, or on which the sand has 
 burned, might require three or four hours. 
 
 If the nature of the sand attached to the castings 
 makes it seem probable that they will require a longer im- 
 mersion in the acid, weaken it by adding water to a point 
 
TINNING. 77 
 
 where there can be no possible danger of the castings 
 being affected in the way mentioned in the beginning of 
 this subject. 
 
 T and U in Fig. 33 are the tanks designed for treat- 
 ing the castings with hydrofluoric acid. If it is found 
 impracticable to get this acid the work may be done with 
 sulphuric acid, in which case the arrangement for its use 
 will occupy the same position as designated for hydro- 
 fluoric acid. 
 
 CLEAXIXG SANDY CASTINGS W^ITH SULPHURIC ACID. 
 
 If sulphuric acid is used to free the castings from sand 
 place them on an inclined, raised platform, which platform 
 should be of a size to accommodate the intended produc- 
 tion and arranged to allow the solution to flow back into 
 the tank placed at the lowest point to receive it. Make the 
 solution in the proportion of i of acid to 6 of water, and 
 keep the castings wet with this solution until the sand is 
 readily removed by the application of water. Gray iron 
 castings cleaned in this way will have a soft, gummy de- 
 posit on the surface, and will not take as perfect a coating 
 of tin as castings cleaned by dry tumbling or by the use 
 of hydrofluoric acid, and they must be given a special 
 treatment before tinning, which will be described in con- 
 nection with the treatment for castings made with rosin 
 cores and hard and greasy castings. 
 
 After the castings have been freed from sand in some 
 one of the ways described, provided they are not exces- 
 sively hard castings or made with rosin cores, are not 
 greasy or " pickled " with sulphuric acid, and have not 
 been faced with black lead facing, then they are ready for 
 tumbling in the solution of muriatic acid, sal ammoniac 
 and water. If any of these conditions exist they must 
 
78 GALVANIZING AND TINNING. 
 
 be given a treatment in a bath of hot caustic soda or 
 soda ash. 
 
 THE USE OF A HOT ALKALI BATH IN CERTAIN CASES. 
 
 If castings have been overpickled — that is, left in the 
 pickle until the surface has become covered with a soft, 
 gummy substance — or if rosin cores have been used in mak- 
 ing the castings or black lead facing used to give a 
 smooth surface, or if grease or paint is present, they must 
 be immersed for several minutes in a boiling solution of 
 caustic soda or soda ash. Make the solution very strong, 
 and see that the strength is maintained by adding fresh 
 material as needed. 
 
 After this treatment the castings must be thoroughly 
 washed with clean water before they are placed in the 
 barrel used to prepare them for tinning. D in Fig. 33 
 designates the tank to be used for the hot alkali solution 
 and F in the same illustration is the tank used for rinsing. 
 
 PREPARING THE CASTINGS IN THE GAS BARREL. 
 
 The details of cleaning having been carefully attended 
 to, place the castings in the tumbling barrel, together with 
 a quantity of ordinary " stars," such as are used in dry 
 tumbling, being careful to load the barrel in such a way as 
 to prevent breaking or w^earing the corners of the castings. 
 Tea kettles should be filled full of the stars or shot before 
 placing them in the tumbling barrel and light, delicate 
 castings should be packed tight enough to prevent break- 
 ing. Stars or shot sufficient to fill the barrel about one- 
 fourth full will be found the most desirable quantity for 
 ordinary work, although on hollow ware much more is 
 needed, or enough to take up nearly all the vacant space. 
 After the barrel has been loaded in the way described put 
 
TINNING. 79 
 
 in sufficient water to fill it about three-fourths full, then 
 add to the barrel 15 pounds of commercial muriatic acid 
 and 2 pounds of gray granulated sal ammoniac. The 
 barrel is now ready to be closed and started, presuming 
 that the operator has examined the valves to see that they 
 are in perfect working order previous to loading the 
 barrel. 
 
 After the barrel has been in motion from 5 to 15 min- 
 utes, depending on the temperature of the water used, 
 there will be formed sufficient gas to cause the valves to 
 open. The escape of gas will be accompanied by quanti- 
 ties of the solution, and the end of the barrel on which 
 the valves are placed should be inclosed, unless the barrel 
 is set up in a different room from the rest of the outfit. 
 
 The time that the castings should be rolled in this solu- 
 tion varies from two and one-half to five hours. Soft 
 smooth castings will take a nice coating after a prepara- 
 tion of two and one-half hours, while to obtain the same 
 results on hard iron, iron cleaned by the use of sulphuric 
 acid, hollow ware and tea kettles and castings having a 
 black lead facing, five hours in the barrel are necessary. 
 It is safe to say that three and one-half hours will properly 
 prepare ordinary castings, the barrel making 40 revolu- 
 tions a minute. For hollow ware, tea kettles and very 
 delicate castings the barrel should not attain a speed of 
 over 30 revolutions per minute. After the castings have 
 been rolled in the solution the required time open the 
 barrel and cover its contents with water immediately. 
 Do not let any time be wasted in getting the castings cov- 
 ered with water, as a slight exposure to the air will cause 
 them to oxidize and prevent them from taking the tin. 
 If the castings are properly prepared—that is, if they 
 have been rolled in the solution long enough — they will be 
 
So GALVANIZING AND TINNING. 
 
 in such a condition after rinsing that they will not soil a 
 white cloth to any extent. 
 
 As soon as the operator has determined whether the 
 castings will tin properly (which is done by putting one or 
 two of the pieces through the regular treatment) he will 
 proceed to dump the contents of the barrel into the receiv- 
 ing tank, located directly under the barrel. This tank is 
 designated in Fig. 33 as B, and should contain about one- 
 third more cubic feet than the rolling barrel. From this 
 receiving tank the castings should be removed to the stor- 
 age tank designated C in Fig. 33. A good sized coke 
 fork is best for handling the castings from tank to tank 
 as it lets the shot or stars fall to the floor and separate 
 from the castings. 
 
 In placing the castings in the storage tank care should 
 be taken to have those with depressions or cavities go 
 under the water with the depressions or cavities up. In 
 other words castings of a shape that would admit of a 
 particle of air being retained should be so placed that no 
 air will be retained. If this occurs there will be a rusty 
 place form on the casting to which the tin will not adhere. 
 Should it be found that the castings are not properly pre- 
 pared the barrel should be recharged by adding 6 pounds 
 of muriatic acid and allowed to run about an hour longer. 
 
 The important point to be kept in mind in preparing 
 cast iron for tinning is that the surface of the iron must 
 be made perfectly clean. Not only clean from sand and 
 rust, but from every foreign substance. It may seem to 
 the reader that we are dwelling on this point unneces- 
 sarily, but only by the most careful attention to the proper 
 preparation of the castings and in keeping them in the 
 same clean condition until they receive the first coat of tin 
 can perfectly satisfactory work be obtained. 
 
TINNING. ol 
 
 If the iron is allowed to roll in the solution too long a 
 time the surface becomes soft from the action of the acid, 
 and the tin will not take. The same trouble will be ex- 
 perienced if the solution in the rolling barrel is too strong, 
 or if the castings are allowed to remain in the solution 
 too long after they are rolled. In rolling the castings cal- 
 culation should be made to complete the work before the 
 stopping of the power at noon and night. Three and one- 
 half hours being required on an average to prepare most 
 iron in the rolling barrel, it is easy to arrange to start the 
 barrel in time to complete one batch in the morning and 
 one in the afternoon. This would furnish work enough 
 to keep two hands engaged, although one set of kettles 
 would take care of all the iron that could be prepared in 
 a barrel the size we show — viz., 2 feet in diameter by 4 
 feet in length. 
 
 If the castings are quite soft and clean three batches 
 may be prepared in ten hours, in which case the second 
 batch should be in the barrel in time to give it at least 
 one hour's rolling before the power is stopped at noon. 
 When a batch of iron is left in the barrel during the noon 
 hour, leave the barrel closed, and in a position where one 
 of the valves will be up or the opening above the solution 
 in the barrel. Unless this is done the valves may open 
 and allow the solution to escape, necessitating recharging 
 the barrel. If the batch is not completed in season to 
 remove it to the storage tank before the time for stopping 
 the power at night, remove the cover, and allow enough 
 fresh water to flow into the barrel to displace at least half 
 of the solution, and leave it in that condition until morn- 
 ing, taking care that the valves do not leak, that the iron 
 is completely covered, and that the water is not left run- 
 
82 GALVANIZING AND TINNING. 
 
 ning, as iron will rust in running water even if the water 
 covers it. 
 
 In rolling a batch of iron it will often be found that 
 a black foam will rise to the surface of the solution when 
 the barrel is opened. This is from the iron dust left on 
 castings that are cleaned by dry tumbling, and it will also 
 be found in preparing castings that have been faced with 
 foundry facing of any sort. When this foam or scum 
 is present, let water flow into the barrel, with the opening 
 in such a position as to allow the objectionable matter to 
 pass ofif. The first one or two batches prepared in a new 
 barrel arc liable to give trouble in tinning unless the in- 
 side of the barrel, with the shot to be used, is cleaned with 
 a strong alkali solution. The simplest way is to put the 
 shot into the barrel, and after filling it about half full of 
 strong, hot alkali solution, close the barrel, and allow it 
 to run an hour or more, after which the interior of the 
 barrel and the shot used should be rinsed with plenty of 
 clean water. 
 
 Where castings are tinned for the purpose of electro- 
 plating them it is desirable, if an extra smooth surface is 
 desired, to give them a rolling in gravel and water in the 
 ordinary wet rolling barrel, although this treatment is 
 not necessary in order to prepare them to take a coating 
 of tin. In treating castings in this way use a coarse hard 
 gravel, and some castings may be rolled 20 to 30 hours 
 to good advantage if the barrel is properly loaded. 
 
 It sometimes happens that castings are encountered 
 that have a ground work of delicate design into which 
 the sand has burned. If such are placed in the rolling 
 barrel with a good quantity of shot and given two or 
 three hours' rolling in a solution of hydrofluoric acid and 
 water, i part acid to 75 or 100 of water, they will be 
 
TINNING. 83 
 
 cleaned very nicely. Where this is clone let the hydro- 
 fluoric solution run out of the barrel before charging it 
 with the regular solution of muriatic acid, sal ammoniac 
 and water. 
 
 The operator must bear in mind at all times, as a safe- 
 guard against accident, that he must see that the valves 
 on the rolling barrel are in working order previous to 
 loading the barrel. These valves should be adjusted to 
 open at a pressure of 40 pounds. If by reason of a leak 
 in any part in the barrel gas is not generated the work 
 will not tin properly. Do not approach the barrel with a 
 light at any time when the gas is escaping, or at any time 
 when the gas is being generated in the barrel. If after 
 stopping the barrel it is found that the valves leak, as 
 they may from becoming clogged, stop the leak, as the 
 solution will escape, allowing the work to oxidize. Badly 
 oxidized castings will not tin. The solution contained 
 in tank F, Fig. 33, is calculated to remove a light oxide. 
 but castings that are heavily oxidized must be rerolled. 
 
 COATING THE CASTINGS W^ITII TIN. 
 
 The tin in the kettles being at the proper heat for the 
 work in hand, as specified later on, the operator takes a 
 small quantity of the castings from the storage tank C. 
 Fig. 33, and places them in the wire basket designated A 
 in Fig. 13, taking care to place those having concave sides, 
 holes or depressions so that none of the various solutions 
 through which they are now to pass will be retained. 
 The castings contained in the wire basket must now be 
 immersed in the solution of caustic soda or potash, re- 
 ferred to in connection with the treatment for greasy, 
 hard or lead faced castings, which solution is contained in 
 tank D, Fig. 33. This solution must be kept at the boil- 
 
84 GALVANIZING AND TINNING. 
 
 ing point, and from one to two minutes is sufficient time 
 to leave the castings in. The best plan for heating this 
 solution is to have a steam coil in the bottom of the tank, 
 as shown in the illustration, and to allow the exhaust steam 
 to pass into the rinsing tank, which is placed directly be- 
 side it, as shown in the ground plan. The rinsing tank 
 is designated E in Fig. ;^7,. After the castings have stood 
 in the alkali bath contained in tank D the desired time 
 they are placed in the rinsing tank E until all traces of 
 that solution are removed. This will take the fraction of 
 a minute provided a stream of water is kept flowing into 
 the tank, as it should be. 
 
 The next move is to immerse the castings in a very 
 weak solution of muriatic acid and water, i part acid to 
 40 of water. The castings must not be allowed to stand 
 in this solution more than two or three seconds. The tank 
 to contain this solution is designated as F in Fig. ^^.' 
 
 Next place the castings in the tank G, Fig. ^^, which 
 contains muriate of zinc, to which has been added 5 
 pounds of gray granulated sal ammoniac for every gallon 
 of the muriate. jMuriate of zinc is made by dissolving 
 zinc in muriatic acid, allowing the acid to dissolve all the 
 zinc it will. For the purpose of making this cut acid an 
 earthen crock can be employed, or an oil barrel sawed in 
 half will answer the purpose. 
 
 The castings are now ready to be immersed in the 
 molten tin contained in the first kettle and shown in Fig. 
 33 at H. The tin in this kettle should attain a heat of 
 500 degrees F., and this heat should be maintained during 
 the time the kettle is in use. 
 
 Before immersing the castings in this kettle the sur- 
 face of the tin should be covered by a flux made by boil- 
 ing a quantity of the muriate of zinc on top of the molten 
 
TINNING. 85 
 
 tin, and adding quickly to the boiling mass a quantity 
 of white granulated sal ammoniac. The sal ammoniac 
 must be added by sprinkling it on before the acid is evap- 
 orated by the heat of the tin. It will take a little time 
 and experience before the proper consistency of this flux 
 can be attained. The proper combination of this flux 
 is one of the most essential points in the successful coat- 
 ing of the cast iron in this first kettle of tin. If the flux 
 is allowed to become hard and dry, as it soon will by con- 
 tinued use unless careful and constant attention is given 
 to it, the flux will adhere to the castings as they pass 
 through it into the tin below, and thereby prevent them 
 from coating. 
 
 When it is found that the flux is becoming thick and 
 lumpy add a sufficient quantity of the muriate of zinc and 
 powdered sal ammoniac to cause the flux to boil up to a 
 depth of y2 inch or more. When this result is obtained 
 take a perforated iron skimmer and carefully remove any 
 hard lumps and congealed matter remaining in the flux, 
 allowing such as readily pass through the skimmer to re- 
 main in the kettle. The purpose of this flux is to pre- 
 vent the surface of the tin from becoming oxidized by 
 exposure to the air, and also to prevent the hot metal 
 from spattering and burning the operator when the wet 
 castings come in contact with the tin. Keep carefully in 
 mind that this flux must at all times be kept in a thin 
 liquid condition, otherwise the succeeding operations 
 through which the castings are to pass before they are 
 completed will be unsuccessful. 
 
 In placing the castings in this first kettle of tin care 
 should be taken to get them immersed as soon as possible. 
 If they are allowed to float on the surlace of the tin the 
 muriate of zinc with which they are wet (for the purpose 
 
86 GALVANIZING. AND TINNING. 
 
 of causing the tin to adhere) will dry off, and the tin will 
 not adhere to that part of the casting left exposed. The 
 work must be kept below the surface of the tin until it 
 has become as hot as the tin itself, and until the tin has 
 ceased to bubble or to be agitated by the castings that are 
 immersed. This boiling or agitation will cease when the 
 air is expelled from the iron and the flux that adhered to 
 it as it passed through has risen to the surface of the tin 
 again. 
 
 The proper way to immerse the work in this first ket- 
 tle of tin is to rest the handle of the basket containing it 
 on the edge of the tin kettle, elevating the basket at an 
 angle that will prevent it touching the molten tin until the 
 operator is ready to have it. Cant the basket so that one 
 of the lower corners will enter the tin first ; in other words, 
 do not allow the bottom of the basket to come directly onto 
 the surface of the tin, as the effect of having so much wet 
 metal as the bottom of the basket presents come in con- 
 tact with the molten tin will be an explosion, resulting 
 most likely in the serious injury of the operator or any 
 one standing near. When the basket is in the described 
 position lower it carefully until i inch or 2 inches of the 
 bottom and one side is immersed in the tin, then lower 
 rapidly, but steadily, until the basket and its contents are 
 completely immersed. 
 
 At this point turn the basket completely over, bottom 
 up, and, using the edge of the tin kettle as a rest for the 
 handle, lift the basket from the tin. When the basket is 
 free turn it bottom down and use it in that position to 
 keep the castings it contained below the surface of the tin. 
 Fill the kettle as full of castings as it will hold and allow 
 them to be completely immersed. Several of the wire 
 
TINNING. ^7 
 
 baskets may be employed to insure having a batch ready 
 to immerse wlien the previous one is disposed of. 
 
 It sometimes happens that the operator carelessly omits 
 dipping- the work in the cut acid contained in tank G, Fig. 
 ^^ ; that is, he may attempt to immerse the work in the 
 molten tin directly from tank D, E or F. Such neglect is 
 dangerous and likely to be attended with serious results to 
 the operator, from the hot metal spattering. 
 
 There are many kinds of work that may be strung on 
 wires and handled through the different stages without 
 the use of the wire baskets. When wires are used the 
 shape may be varied to suit conditions. While we show 
 the most common in Fig. 13, the ingenuity of the operator 
 must be employed in selecting those best adapted to his 
 wants and in devising others for himself. 
 
 The kettle being full as described, the castings must 
 remain where they are from 5 to 15 minutes, or until they 
 have taken a perfect coating of tin. If in this time they 
 are not properly coated, some error has been committed in 
 the previous operations and the work must be reroUed. 
 
 What dross or slag forms in a tin kettle rises to the 
 surface. A considerable part of this objectionable matter 
 will be found in the first kettle, which must be removed 
 before the work can be carried to the finishing kettle or 
 kettles. To accomplish the removal of this dross or slag, 
 floating on the surface of the tin, use a perforated, concave 
 iron skimmer. The holes in the skimmer should be large 
 enough to allow the clear tin to flow through freely, and 
 care should be taken not to waste the flux in skimming out 
 the dross. If the skimmer is canted edgewise as soon as 
 the clear tin passes off the slag will adhere to the skimmer 
 and the flux will flow back into the kettle. 
 
 When all the slag has been removed grasp one of the 
 
88 GALVANTZTNG AND TINNING. 
 
 castings with a pair of tongs and remove it with a quick 
 motion from the tin. If wires have been employed and 
 the work is strung, take one or more wires and remove in 
 the same way to the next kettle, taking care that no flux or 
 dross is carried along with the work. The temperature 
 of the tin in the first kettle is much too high for finishing 
 the work, and when the castings that are taken from this 
 first kettle are exposed to the air they will be more or less 
 yellow, depending on the heat of the tin. A bright yellow 
 or golden color indicates too high a heat of the tin and 
 must be avoided. A slight yellowish tinge indicates the 
 proper heat. 
 
 The tin in the second kettle, which is designated in Fig. 
 33 as K, and which is, in most cases, the finishing kettle, 
 must be maintained at a temperature of about 400 degrees 
 F., and the surface kept covered to the depth of from ^ to 
 I inch with pure beef tallow. Palm oil may be introduced 
 into the tallow with good results, using of the latter about 
 10 per cent. The operator retains the castings held by the 
 tongs or wires immersed in this second kettle one or two 
 seconds and then, with the tongs held in the left hand, he 
 removes the piece from the tin. As soon as the piece is 
 clear of the tin the operator grasps it with a pair of tongs 
 held in the right hand, and with a few rapid swinging 
 motions to free the article from surplus tin, he plunges it 
 into a tank containing kerosene oil. If wires are being 
 employed he swings the work to and fro rapidly to free it 
 from the surplus tin, and when plunging it into the oil he 
 must give the work a motion calculated to prevent the 
 articles in contact from adhering to each other. 
 
 The tank, which is designated in Fig, 33 as L, in con- 
 nection with a companion tank M, should be of sheet iron 
 and placed in the companion tank M with a view to having 
 
TINNING. 89 
 
 a body of water surrounding it to keep the oil from becom- 
 ing heated, as it soon would be from the hot castings 
 constantly immersed in it. The work must be immersed 
 in this oil long enough to set the tin and then immersed in 
 the cold water contained in the companion tank M. 
 
 If the tin in this last or finishing kettle is at the right 
 temperature the work will be white and have a nice luster 
 after it is cooled. If the work is rough and lumpy it indi- 
 cates that the tin in the finishing kettle was not hot enough 
 or that the work was kept in the air too long a time before 
 dipping it in the oil. The tin in the finishing kettle 
 requires very little fire to be maintained as there will be 
 nearly enough heat in the castings when they come from 
 the first kettle to keep the tin in the second at a proper 
 heat. If the work is yellow after cooling in the oil, it may 
 indicate too high a heat in the finishing kettle, or it may 
 indicate that the casting was not kept in the finishing ket- 
 tle long enough to bring the heat that the casting attained 
 in the first kettle down to a point where the tin would not 
 be yellow. 
 
 The work will come out of the finishing kettle smoothly 
 and brightly coated even when the temperature of that 
 kettle is so low that if a piece of cold iron be put in the tin 
 would adhere to it in a mass. The heat the castings attain 
 in the first kettle makes it possible to run the finishing 
 kettle at a very low temperature and it is desirable to do so 
 on very heavy castings. Light castings require, of course, 
 that a much higher heat be maintained in the finishing 
 kettle than is necessary on heavy castings. The reason is 
 apparent : Light castings must be exposed to the air a few 
 seconds while the operator is switching ofif the surplus tin, 
 and being light, they, of course, do not hold the heat long 
 
90 GALVANIZING AND TINNING. 
 
 enough to allow the surplus tin to be shaken off without 
 leaving rough, ragged edges. 
 
 A great deal of ingenuity can be displayed by the 
 operator in handling castings of various shapes in such a 
 way that no lumps or bunches of tin will remain on the 
 work after it is cooled. For example, in grasping the 
 article to be cooled care should be used to find what part 
 of the casting is best adapted to be taken hold of by the 
 cooling tongs without marks of the tongs being left after 
 the article is cooled. The tongs used for cooling should 
 never be put into the tin kettle, as the heat of the casting 
 would cause it to adhere to the tongs if they were tinned. 
 After shaking off the surplus tin change the position of 
 the casting so that the drop of tin, which will naturally col- 
 lect at the lowest point, will flow back ontiD the casting and 
 dip in the oil at once when this is s.ccomplished. 
 
 A '* switching box " should be employed when 
 " strung " work is being handled to catch the tin that is 
 thrown from the work in the operation of " switching " 
 it to throw off the surplus tin. This box is a very simple 
 arrangement. Its position when in use is designated D, 
 Fig. 25. Cover the interior of the box with heavy paper, 
 as the hot tin will stick to the wood unless paper is used. 
 The tin thus collected may be thrown into 'the kettle 
 together with the paper when the tin is needed for use. 
 
 When the castings have been finally cooled as already 
 described, they should be immersed in a tank of boiling 
 water to free them from oil and also to remove any trace 
 of acid that may be on them. This final rinsing tank is 
 designated X in Fig. 33. The water must be kept clean 
 and at the boiling point at all times when in use. An 
 ordinary foundry riddle with upright handles long enough 
 to allow the operator to set the riddle, with the work to be 
 
TINNING. 91 
 
 treated, into the tank without scalding his hands, may be 
 employed to immerse the work in this tank. 
 
 The castings should be dried off in clean dry sawdust, 
 and for this purpose use sawdust made from pine or some 
 soft wood, as hardwood sawdust will scratch the tinned 
 surface. The drying box is shown at O in Fig. ^^. 
 
 When three kettles of tin are employed, as they may be 
 to good advantage in tinning work that is designed to be 
 plated, the second kettle must be run at a temperature of 
 450 degrees F. The surface of the tin in this kettle must 
 be kept covered with an acid and sal ammoniac flux the 
 same as the first kettle. The castings in the first kettle are 
 to be passed in quantities to the second kettle, there to re- 
 main until the first kettle is refilled. The same care must 
 be taken not to allow any of the slag or flux that accumu- 
 lates on the first kettle passing with the work to the second 
 kettle, and the tin in the second kettle must be kept free 
 from slag. 
 
 The tin in the third or finishing kettle should be main- 
 tained at a temperature of 400 degrees F., and the depth 
 of the tallow increased to 3 or 4 inches. 
 
 If three kettles are employed they should be square or 
 round and arranged to fire from one side, instead of at 
 the ends. 
 
 The water in storage tank C. Fig. ^^, will in a short 
 time become charged with the acid solution from the roll- 
 ing barrel unless it is changed frequently. If much acid 
 is present in the water it will impair the alkali solution 
 into which the castings pass directly from the storage 
 tank. If a few pounds of the alkali selected for use 
 (caustic soda or soda ash) is added two or three times a 
 week the alkali will do its work properly for some time, 
 although it is best to clean out the tank and make the solu- 
 
92 GALVANIZING AND TINNING, 
 
 tion Up fresh once in two weeks w^here it is in constant 
 use. 
 
 In rinsing the castings in tank E, Fig. 33, do not let 
 them remain in a great length of time if water is flowing 
 in, as iron will soon rust in running water. The solution 
 in tank F, Fig. 33, should be made up fresh after 2 or 
 3 tons of iron has passed through it, and, as already stated, 
 the castings should not be allowed to stand in this solution 
 more than two or three seconds. 
 
 The solution of muriate of zinc contained in tank G, 
 Fig. 33, should be deep enough to cover the castings con- 
 tained in the wire basket used to immerse them in the 
 first kettle, and the solution should be kept in good con- 
 dition — that is, care should be taken not to allow it to be 
 weakened to any great extent by the solution in tank F 
 passing into it with the work. The tank containing this 
 muriate of zinc should be lead lined and an inner lining 
 of wood used to protect the lead lining. 
 
 As it is almost impossible to make castings that have 
 been imperfectly coated at the first attempt take a satis- 
 factory coating of tin, the operator should give careful 
 attention to details. 
 
 It is possible by practice to keep the tin at a proper 
 heat, but the operator will find more difficulty in doing 
 this than any other one thing in the entire operation. That 
 the proper heat be maintained is very essential, for if it is 
 not, all previous care in preparing the iron will have been 
 in vain. If too hot the flux on the first kettle of tin will 
 evaporate or burn off, and the tin will not take to the iron. 
 If too high a heat is reached on the kettle containing the 
 tallow, tl e tallow will be set on fire. As a help to a nov- 
 ice and, in fact, to an experienced man, we recommend 
 the use of a pyrometer, one for each kettle. The expense 
 
TINNING. 93 
 
 of providing them is not to be considered in comparison 
 with the advantages obtained. 
 
 The kettles for containing the tin may be, and usually 
 are, of cast iron, although fire box steel is often employed 
 to make oblong kettles. 
 
 A floor space of 20 x 40 feet will accommodate a tin- 
 ning plant running two rolling barrels. If possible, the 
 plant should be located handy to power and with a view 
 to obtaming easy and perfect drainage. If necessity com- 
 pels the setting up of the plant in the factory building 
 above the ground floor, as is sometimes the case, the floor 
 of the tinning room must be so constructed that leakage 
 into the room or rooms below will be prevented. 
 
 The dross or slag formed in the kettles should be 
 stored away until a suflicicnt amount is accumulated to 
 make profitable the remelting of the slag for the purpose 
 of reclaiming what pure tin is in it. For the purpose of 
 remelting this dross the pure tin can be removed from 
 the kettle H, Fig. 33, and the dross melted up in it. When 
 the entire mass is in a molten state, and at a temperature 
 of about 550 degree F., bail off the liquid tin into cast 
 iron pans provided for that purpose, and what dross re- 
 mains into separate pans. This tin dross has a market 
 value of from 40 to 50 per cent, of the price of pure tin. 
 
 With the addition of tanks for containing acids a 
 plant built to tin cast iron is adapted to all descriptions 
 of tinning, except retinning of tinware and the tinning of 
 sheets. 
 
OCT 19 1900 
 
LIBRARY OF CONGRESS