TX 763 .884 Copy 1 A HANDY MANUAL OF UP-TO-DATE MONEY-SAVING SUGGESTIONS AND FORM-SHEETS FOR SMALL AND LARGE BAKERIES, THE RESULT OF YEARS OF STUDY AND PRACTICAL EXPERIMENTS PART 5 Heat, Combustion, Fuel, Ovens, BY EMIL BRAUN (Expert and Consulting Baker) Author of "Perfection in Baking," "The Baker's Book," Vols. I. and II. Published By EMIL BRAUN Cincinnati, Ohio 1911 ip%" *! Copyright, 1911 by EMIL BRAUN Cincinnati, O. ©CIA 283227 PART 5. Heat, Combustion, Fuel, Ovens. — HEAT. The introduction of machinery and patent bake- ovens necessarily demands of the up-to-date baker a more or less technical education. The regulation of the temperature of water, sponge and dough, as well as the regulation of heat in bake-shops and the ovens, must be studied, and the principles governing them properly applied. The heat in a bake-oven can and should be kept under control just as the engineer has perfect control over his engine or boiler. A pyrometer or thermo- meter should be attached to every bake-oven, whether made of brick or iron; indirectly (flue-heated) or in- side (direct) fired. There are three different scales of heat measure ; the Reaumur, Celsius or Centi- grade and the Fahrenheit. To abbreviate these names on pyrometer or thermometer, the following letters are used: R. (Reaumur), C. (Celsius), F. (Fahren- heit). The freezing point on the R. and C. is marked at zero, 0, while on the F., it is 32 degrees above zero. The respective boiling points are marked at R. 80 de- grees, C. 100 degrees, F. 212 degrees. In R. and C, reading the number of degrees below zero are marked "Cold,'' or "Minus" ( — ) degrees. Those above are marked "Heat," or "Plus" ( + ) degrees. By this you can readily understand how important it is to men- tion the system of "Scale" used when speaking of temperature. To transform degrees of Fahrenheit into Reau- mur, you deduct 32 from the F. degrees ; multiply the remaining number by 4, and then divide by 9. 2 Part 5 For example: 77 degrees F. are equal to 20 R; de- duct 32 from 77, equals 45; multiply with 4, equals 180; divide by 9, equals 20. To transform Fahrenheit into Celsius, deduct 32 ; multiply by 5, and divide by 9. To transform Celsius into Reaumur, multiply by 4, and divide by 5. To transform Celsius into Fahren- heit, take the number of C. degrees 1 4-5 times, and add 32. To transform R. degrees into C, take the num- ber of R. l}i times. R. degrees are transformed into F. ? by taking the number of R. degrees 2% times and add 32. Mercury has been adapted as the standard for use in thermometers, due to the regular and never- varying way in which it expands or contracts under normal conditions. The column of mercury in the tube of a thermometer seems to be round, and about one-sixteenth of an inch in diameter. As a matter of fact, it is flat, and a good deal finer than a single hair. Mercury does not expand to any great extent so it is imperative that we confine it in as small a space as possible. It is the magnifying effect of the glass that enables us to see it so plain. Spirits of wine, is sometimes used, with coloring matter added, but -it is not perfectly accurate. Up till a few years ago, Mercury Thermometers for bake-ovens were not extensively used, owing to their frail construction and liability to breakage as well as constant separation of the mercury column. Mod- ern manufacturing methods and new invention along this line have overcome these defects. There are now on the market two distinct styles of heat records. They are the Angle Thermometer and the Improved Pyrometer. In classing the heat indicators on the market to-day in two styles, I reserved the "Electric Pyrometer" for a class in which it stands alone. With this instrument, the height of achievement has cer- Part 5 3 tainly been reached. In most shops, while the oven- man is responsible for the appearance of goods coming from the oven, it is the foreman in charge who gets the blame for things going wrong. Think of the saving of time and worry for the foreman or superin- tendent who has such diverse things to keep his mind on, to be able at a moment's notice to stand at one end of a chain of ovens or in his office and see the temperature of every oven in the shop by simply throwing an electric switch. Could we wish for any- thing more simple and satisfactory? The movements and all parts subject to heat on these as well as the modern thermometers and pyrometers now on the market are made of non-corrosive material. They are all very sensitive, and the indicator shows instantly the slightest variation in temperature. The proper degree of heat for baking and handling of the above instruments will be more thoroughly mentioned under "Ovens and Firing. ,, It appears that this part of the shop system has been grossly neglected in most bak- eries, both large and small. If the firing of different styles of ovens is properly understood, a more uni- form heat is acquired and a great saving in fuel is the result. Very few bakers have paid any attention even to the first principles of combustion and heat units. However, before we go into details of correct firing methods and kinds of fuel, a few facts on the principles of combustion will be necessary. COMBUSTION. Chemists classify all known substances either as elements, compounds or mixtures. We will deal only with the elements and compounds. Compounds are those substances which can by chemical action or by action of physical energy (heat or electricity) be di- vided into two or more simpler substances. These substances which cannot by any known means be further split up are called elements. The principal 4 Part 5 elements we have to deal with in the combustion of fuel are: Carbon C. Hydrogen H. Oxygen O. Sulphur S. In referring to these elements, it is customary to use the symbol or abbreviation which is usually the first letter. Thus, C stands for Carbon, and O for Oxygen. Popularly, combustion means fire or burning. Ex- clude air from a fire, and the fire goes out. Oxygen is therefore necessary for combustion. Science has proved that oxygen has a great attraction for carbon, therefore, when these two elements are exposed, they rush together with great rapidity and force, and the chemical action is accompanied by light and heat. In combining in this way, they form an invisible gas, called carbon dioxide. The chemical symbol of this is CO2 . From this we plainly see that for every part of C or carbon present, we must have two parts of O, or oxygen. If we do not have these proportions pres- ent, a different gas is formed, producing through the chemical action, a larger or smaller amount of chemical energy, or heat. For instance, cut off the air supply, until you have but one part of O or oxygen for each part of C, or carbon, and these two uniting, form the gas Carbon Monoxide, the chemical symbol of which, is CO. When this occurs, that is, when less air is sup- plied, the combustion is said to be imperfect, and the carbon burns to CO instead of CO2. The quantities of heat produced by the complete combustion of carbon in our fuel, is found by experiment to be as follows : Carbon burned to CO2 generates 8080 calories, or 14500 B. T. U. Carbon burned to CO generates 2473 calories, or 4452 B. T. U. By this you see we lose 5607 calories or 10,000 B. T. U., if the supply of air is not sufficient to burn it Part 5 5 from CO to CO 2. Calories is the standard name in referring to the table of Heat Units. A calorie of heat is the amount of heat required to raise the temperature of one gram of water, from degrees to one degree, Centigrade. This is called the Gramme-Calorie or lesser calorie. For measuring larger quantities of heat, just the calorie is used. This is the amount of heat neces- sary to raise one kilogram of water, through one degree of Centigrade. The Gramme-Calorie is 1-1,000 part of the Calorie above mentioned. There is another system of heat units used among engineers that depends entirely on British standards of weight and temperature. This is called the British Thermal Unit, and is abbreviated B. T. U. One B. T. U. represents the amount of heat required to raise one pound of water through one degree F. To transform Calorie Units (metric system) into British Thermal Units (Fahrenheit degrees) multiply the former by 9 and divide by 5. Usually the quantity of air admitted to the furnace, is from 50 to 100 per cent more than is necessary for the complete combustion of the fuel. This extra quan- tity of air enters the furnace at a temperature of from 60 to 70 degrees and escapes up the chimney at a temperature of from 400 to 600 degrees. A large quantity of heat is thus wasted and the temperature of the fire lowered. So you see that by being careful not to get too much draft, you overcome the loss of heat the same as by being careful that you have enough. Following are a few conditions existing in our fuels that aid or retard complete economical combustion, and they should be understood by all bakers. The conditions necessary to consume the gases generated are the same as for the burning of the car- bon, that is, a sufficient supply of air, allowing it a chance to mix with the gases at a high temperature in the furnace box. Be sure that your fuel is not wet. The moisture of the fuel must be evaporated at the expense of the G Part 5 heat produced by combustion. This moisture enters the furnace at the prevailing outside temperature, say 70 degrees, and passes up the chimney in the form of vapor, at 400 degrees or more. In producing this rise in temperature, thousands of heat units will be lost daily. Therefore, always keep your fuel under cover as far as can be helped, and never expose it to rain. Oxygen and hydrogen are found in fuel in com- bination in the form of moisture. This is one reason for using fuels containing as small a percentage as possible of these two elements. Although black smoke contains quantities of small particles of unburned car- bon, the heat loss is not as great as we might imagine. This is more thoroughly treated under the heading of Firing. Now that we have a little better knowledge as to how our fuel is consumed, we will discuss the various kinds of fuel. Comparative Table of Total Heat Evolved During Combustion. Combustibles 1 Lb. Weight C to CO C to CO Average Coal Coke Wood Weight of Oxygen Consumed per Pound of Combustible Qyantity of Air per Pound of Combustibles. 2.66 1.33 2.46 2.50 1.40 Lb. 11.60 5.80 10.70 10.90 6.10 Air Cubic Ft. at 60° F. 152 76 140 143 80 Total Heat per Pound of Combustible B. T. U. 14500 4452 14133 13550 7792 Part 5 Chemical Composition of Combustibles. PECLET (Authority). Carbon, Hydro- gen Oxygen Nitrogen and Sulphur Water Ash Total Coal (Average) .804 .850 .510 .408 .930 .0519 .0787 .0246 .0408 .150 .020 .016 .070 1.000 Coke 1 000 Wood (Dry) .023 .042 .417 .334 1.000 Wood (Ordinary) Charcoal (Wood) .200 1.000 1 000 FUEL. Fuel is now such an expensive commodity that the economic ways in which it can be used, its quality, and power to generate heat, become subjects of great importance, wherever it is used in large quantities. Fuel, as the word is ordinarily used, means all sub- stances that burn in the air and produce heat. The fuels most commonly used are generally of an organic or vegetable origin. This includes all kinds of coal, peat, wood, coke, charcoal, as well as combustible gase. c and liquid fuels. All fuels consist of more or less car- bon, an element necessary for producing heat. But hydrogen, oxygen, nitrogen, sulphur and ash are all substances found in the above list of fuels, and must be considered, as the quantities in which they are present influences the value of any fuel as a heat pro- ducer. The number of heat units they produce ranges between wide limits, and vary according to the chemi- cal composition. The more organic oxygen present in 8 Part 5 a fuel, the less heat produced, owing to its being in combination with other elements. Sulphur is also an undesirable element in fuel, as it does considerable damage by corroding the grate bars, flues, chimneys and oven fixtures. The more ash a fuel contains, also lowers its value for economic purposes, as less heat is produced and much time is lost cleaning fires and digging out clinkers. Many of the large manufacturing concerns and institutions employing chemists, make a practice of de- termining the chemical composition of their coal. By doing this, they are enabled to buy only those fuels, coal or coke, having the largest percentage of heat- producing elements. This detail work in connection with fuel has not, to the author's knowledge, been adapted by any of our large bakers. I will give a few practical pointers on the compo- sition and action during combustion of various fuels, that may be of interest and value to the baking in- dustry and the manufacturers of bake-ovens. Opin- ions about the most economical fuel for bakers' ovens differ, and local prices of material must be considered in the selection of the fuel. COAL. Coal is divided into four different varieties, the market price of which vary considerable. They are mentioned as follows : 1. Anthracite coal, which contains about 92 or more per cent of carbon. 2. Semi-anthracite coal, over 85 up to 93 per cent of carbon. 3. Semi-bituminous coal, which contains over 70 to 87 per cent of carbon. 4. Bituminous coal, which contains from to 75 per cent of carbon. Part 5 9 ANTHRACITE COAL. Does not ignite so quickly and requires a stronger draft to burn it. It is quite hard and shiny; burning with almost no smoke, gives it the preference over other coal in bakeries. This coal is sold under different names, accord- ing to size into which the lumps are broken. They are named in regard to the dimensions of the screens over and through which the lumps of coal will pass, for instance : PEA passes over y 2 -'mch mesh and through 1-inch square mesh. CHESTNUT passes over ^-inch mesh and through \y 2 -inch square mesh. STOVE passes over 1^-inch mesh, and through 2-inch square mesh. EGG passes over 2-inch mesh, and through 3-inch square mesh. Another advantage in using anthracite coal, is the fact, that its available heating power is practically constant. The semi-bituminous coals and all good caking, soft coals yield just about the same quantities of available heating power as does the best anthracite coal, but require more attention and raking and con- sequently the fire and heat is not as constant and uni- form as if the former coal is used. Anthracite is a non-caking coal. As stated, it contains more carbon than any other coal and the least amount of volatile matter (hydrocarbons) from one to ten per cent. The best anthracite coal is mined in the northeastern part of Pennsylvania, in the Lehigh Val- ley, Susquehanna, Shamokin and Lackawanna Dis- tricts. Occasionally, you get some anthracite coal which is flinty and hard as stone. It is almost im- possible to ignite it; just glows like stone and the pieces frequently fly all apart in the furnace with a crackling noise like a gun explosion. Such coal is 10 Part 5 called Graphitic Anthracite, contains from 1 to 2 per cent of gaseous matter and as a fuel is almost worth- less. Graphitic Anthracite is found more frequently in the New England coal fields, especially in the Rhode Island Basin. SEMI-ANTHRACITE coal has about the same composition as the anthracite, but, is not as hard and burns more quickly ; it crumbles readily and is not as clean, but burns with little smoke. Contains from 8 to 12 per cent, of volatile hydro-carbons. BITUMINOUS COAL. SEMI-BITUMINOUS coal containing from 12 to 25 per cent, of volatile hydro-carbons is easily ig- nited, burns freely with little or no smoke and is used extensively for heating steam boilers. This coal forms a hollow fire. BITUMINOUS COAL contains the most volatile hydro-carbon, varying from 20 to over 75 per cent. The nature and composition of this coal varies more than any other kind of fuel, therefore they are divided into three distinct classes: 1. Caking Coal are those which swell and fuse together, forming a solid, spongy mass when burned in the furnace or grate. Therefore the fire must be frequently broken down with a slice bar and cleared from the grate in order to admit the air to pass through. 2. Free Burning or Non-Caking Coal is so called, because it does not cake together as the above men- tioned varieties. 3. Cannel or Gaseous Coal is very rich in vola- tile matter or hydro-carbons and therefore preferred for making gas. SLACK is the name given to the dust or left overs from any soft coal after they are screened. LIGNITE or BROWN COAL is the connecting link between Peat and Bituminous coal, the color varies from brown to black, absorbs moisture very rapidly Part 5 11 when exposed to the weather, which causes the lumps to break up and crumble quite readily. It burns quite easy and freely with a yellow flame and emits a tar- like disagreeable odor. However, its heating power is very low and it leaves considerable ash; is classed as a non-caking coal. PEAT is the first product resulting from decayed vegetable matter, partly carbonized and being found in marshes and swamps ; it generally is spongy and satu- rated with moisture, containing on the surface as high as 80 per cent water ; deeper down where it is more de-composed, it is also more solid. Before being fit for transport or burning, it must be dried out, being cut or pressed into brighettes. HARD COAL VERSUS SOFT COAL. When caking coals are burned, they fuse at com- paratively low temperatures, forming a crust over the top of the fire which prevents the immediate escape of the volatile gases that comprise from 40 to 50 per cent of the fuel's heating power. These gases are then driven to the side of the fire-pot where they unite with the rising oxygen and, igniting at that point, are converted into volatile heat- ing power. When free burning coals are used, they disinte- grate at comparatively low temperatures and some of the hydro-carbon gases escape without coming in con- tact with the necessary oxygen for ignition. It makes quite a difference whether the coal is dry or wet. If it is wet, a large percentage of heat is necessary to bring up the temperature of the wet fuel to 212° first, in order to turn the water (dampness) into steam, and as a large percentage of this steam passes through the flues and chimney, that amount of heat is lost for heating purpose. As mentioned before, to raise the heat of one part (say one pound) of water one degree Fahrenheit it takes one Heat Unit. There- fore, if you pour one pound (one pint) of water at 12 Part 5 60 degrees F. over the coal, it takes 152 Heat Units (B. T. U.) to raise the water from 60 to 212 degrees F. or to the boiling point and as it takes about 970 Heat Units (B. T. U.) to evaporate or turn this pint of water into steam, you need altogether 152+970= 1122 Heat Units (B. T. U.) This same example worked out in Calories would read like this : For one Kilogram (one liter) water at 15 degrees Centigrade or Celsius (60 degrees F.) it takes 85 Calories to raise this pint of water from 15 C. to 100 C. or the boiling point, and as about 540 Calories are required to evap- orate or turn all the water into steam, you need alto- gether 85+540=625 Calories, which equals the 1122 British Thermal Units on Fahrenheit bases. This example shows very plain that large quan- tities of heat are lost when damp or wet fuel is used. COKE. Is the residue left from certain kinds of Bitumin- ous coal, when burned or heated with almost the en- tire exclusion of air and all its volatile matter driven off, leaving practically only carbon and a little ash. (see table.) It does not resemble the original coal at all ; is hard, rough and honey-combed, and has a metallic ring, being much lighter than coal. Coke burns with almost no flame when combustion is com- plete. GAS HOUSE COKE is a by product from the manufacture of illuminating or artificial gas and mostly consumed locally. FURNACE COKE used to be made similar to charcoal in piles or mounds, but the demand having steadily increased, large Kilns and Coke Ovens of brick or stone have been erected for its manufacture. The most extensive coke centers are located around Pittsburg in the Connelsville district and the Alle- ghaney Mountain sides. West Virginia also produces considerable coke in the New River and Kanawha districts. Furnace coke is classed and its price fixed Part 5 13 according to the time it has been in the oven. (Car- bonizing.) The standard kinds are known as 48 and 72 hour coke, the latter giving the highest number of Heat Units. Although the price of the 72 hour coke is from 50 to 75 cents per ton higher, it is the most economical, very light in weight, dry and uniform in size. Good Connel'sville coke analizes as follows : Carbon 88.00 to 89.00 per cent Ash 9.50 to 11.00 per cent Volatile Moisture 1.00 to 1.50 per cent Sulphur 0.75 to 0.90 per cent GAS PRODUCER or ILLUMINATING GAS is dis- tilled from coal. On account of its high price it is used very little for heating bake ovens. Its heating value is estimated at about 155 B. T. U. per cubic foot. NATURAL GAS. In sections where a plentiful supply of natural gas has been discovered, it is used very extensively, and to-day is supplied from central stations to cities hundreds of miles away. The only trouble with natural gas is the inconsistency of pres- sure and in some localities the flow has given out en- tirely. Natural gas concerns claim that on an average, 20,000 to 23,000 feet of this gas has the heating value of one ton of coal. The principal constituent is Marsh Gas (Methane) C. LU. The complete or proper com- bustion of natural gas is a problem which kept many scientists and engineers busy and experimenting ever since the introduction of natural gas for heating pur- poses. The combustion of natural gas is a very difficult problem to solve. To be able to use this ideal fuel successfully, - both from a commercial and financial standpoint^ a few fundamental principles must be observed. 1. The proper amount of gas and oxygen must be brought in contact with each other. 2. After being brought together, they must be thoroughly mixed before reaching the point of ignition. 14 Part 5 3. Combustion must take place before they have a chance to separate again, which they will do soon after being mixed. The supply of proper amount of air must be watched, as a natural gas flame cannot exist unless supported by oxygen. Withdraw the air or oxygen supply, and the flame will be extinguished, while the gas will keep on flowing or escaping. Therefore, care must be taken when lighting a gas burner in any inside or furnace oven, that the dampers are first opened and that there is enough draft to carry away the product of combustion, otherwise there will be an explosion. It is a peculiarity of gas explosions that they strike back; that means through the open oven or furnace door. The writer witnessed several accidents as a re- sult of such gas explosions, where the men opened the valves of the burners before they had the lighted torch applied. In bakeovens with direct firing (inside the oven chamber) the danger of explosion is still greater. But nine times out of ten, the man who lights the fire is the cause through his carelessness. The writer al- ways cautioned his men to surely first open damper and oven door for a minute, to let any possible accu- mulation of gas in the oven escape before he puts his torch or light near the burners or grate, and only then open the gas valves. One of my foremen was burned three different times through his carelessness. One time the force of the explosion striking back through the oven door, threw him clear across the shop against the wall, burn- ing his chest and face frightfully. As there may be a leak somewhere, unnoticed, it is the safest way to have an automatic pilot (small flame) burning all the time. Air and gas may be compared to oil and water, as they will not mix unless they are violently agitated, and unless combustion takes place promptly after prop- er amount of oxygen and the carbon in the gas have been agitated, they will separate again and escape with- Part 5 15 out furnishing the desired heat. As stated before, complete or perfect combustion requires the union of one atom of carbon C. and two atoms of oxygen O 2. The gas people claim that they can use nearly 80 per cent of air with their gas. A natural gas from Pittsburg district shows aver- age composition of: Marsh gas (C. H 4 . 67.00 per cent Hydrogen (H) 22.00 per cent. Nitrogen (N) 3.00 per cent. Oxygen (O) 0.80 per cent. Other gases, ,.. 7.20 per cent. There are different styles of gas burners, but they do not all answer the purpose of heating bakeovens. The writer's experience with different gas burners will be explained later on under firing. WOOD. Is not used as extensively nowadays as a fuel for heating bakeovens, as it was before the introduction of Patent Flue and Continuous Bakeovens, except for kindling the fire. In a general way, one cord of the best hard wood is estimated to be equal to one ton of coal ; one cord of soft wood is equal to y 2 ton of coal. B. & W. Co. give a comparison of 2y 2 lbs. of dry wood to one lb. of bituminous coal in heat value. Of course these figures are calculated for heating Steam Boilers. For heating Bakeovens, I find heating value of wood closer to that of coal, especially in inside fired ovens. Green wood contains from 30 to 50 per cent of mois- ture. When perfectly dry, it contains about 50 per cent of carbon. An analysis of Oak has been quoted to be composed of 49 per cent carbon, 6 per cent hydro- gen, 42 per cent oxygen, a little over 1 per cent ash and not quite 1 per cent nitrogen. The heating value of wood varies from about 6,500 B. T. U. to 9,000 B. T. U. or an average of 7,700 B. T. U. per lb. (see tables, pages 6 and 7, part 5.) 16 Part 5 OIL. PETROLEUM is being used only in sections where coal is scarce and oil plentiful, especially in Cal- ifornia, Texas and Wyoming. CRUDE OIL from Pennsylvania contains about 85 per cent carbon, 14 per cent hydrogen, 1.4 per cent oxygen which gives a theoretical heating power of about 20,000 B. T. U. but there is quite a loss of heat by evaporation, which reduces the number of Heat Units considerable. There is also danger of explosion. The Standard Oil Co. es- timate that 173 gallons of their oil equal one long ton (2,240 lbs.) coal, allowing for all savings inci- dental to its use. COMMERCIAL VALUE OF FUEL. The commercial value of a given fuel for a certain amount of baking, can only be determined by an ex- tended trial, keeping careful records, adding to the fuel cost, the cost of firing and removal of ashes. (See Oven Record cards). Keeping a record of same items under same conditions, but with different fuels, it may be found at times, that a low priced fuel can be more expensive than the real high priced on account of requiring more labor for firing and removing ashes, cleaning grate and flues since larger quantities must be burned to get the same amount of heat. Anthracite Coal (small size) bought at $2.50 per ton will furnish about 10,000,000 B. T. Heat Units for $1.00. Larger sizes like Stove and Ee:g at the price of $6.25 per ton furnishes about 4,500^,000 B. T. U. for $1.00. The heat value of various grades and qualities of Bituminous or Soft coal will lie between the above figures or average between 4,000,000 to 10,000,000 B. T. U. for $1.00. Illuminating Gas at $1.00 per 1,000 cubic feet will yield only about 500,000 heat units for $1.00. Natural Gas if sold for 10 cents per 1,000 cubic foot will give about 10,000,000 B. T. U. for $1.00. Part 5 17 Crude Oil selling at 4 cents per gallon will average 4,000,000 heat units for $1.00. Kerosene selling at 10 cents per gallon is equiva- lent to 1,200,000 heat units for $1.00. Nearly all liquid fuels (distillates) furnish about same amount of heat per pound, but vary greatly in cost. One ton of Anthracite coal averages 25 bushel at 80 pounds. One ton of soft coal averages 40 bushels at Go pounds. One ton of coke averages 40-50 bushels at 40 pounds. A " long" ton of coal weighs 2240 pounds, but is only sold on these bases to dealers or car load buyers ; the extra 240 lbs. being figured as allowance for loss or shrinkage. BAKE OVENS, All old time ovens were fired with wood and were built on the same principle as the ovens found to this day in most smaller bakeries in Europe, especially in country districts. These ovens are well filled with dry wood and then fired. When all burned out, the ashes are removed and the oven chamber swabbed out with a wet cloth fastened to a pole. Such ovens are called the old "Vienna" Ovens and are used to this day by a number of Italian and French bakers in this country, even in New York and other large cities. However, with the introduction of modern improvements a great number of different constructed bakeovens have been devised and placed on the market. They may be di- vided into different classes, according to their con- struction, method of firing or kinds of fuel required : 1. DIRECT or INSIDE fired ovens. 2. INDIRECT or FURNACE fired ovens. 3. CONTINUOUS BAKING or HOT AIR CHAMBER ovens. 4. HOT WATER or STEAM PIPE ovens. Then again baker ovens are known irrespective of 18 Part 5 the method of firing or kind of fuel used, under differ- ent names according to their mechanical construction, such as: Portable Ovens, Stationary (Brick) Ovens, Rotary, Reel and Drawplate Ovens, and now we have even Traveling ovens. DIRECT FIRED OVENS.— In this class belongs first the old Vienna Oven as above mentioned, fired with wood. After the fire has been drawn, the oven is allowed to stand off for one half to one hour with door and damper tightly closed, to allow the heat to equalize through every part of the oven chamber. However, after two or three batches are baked, the chamber must be refired again. One german authority even refers to having the oven refired after every batch. His figures are : For first baking, 100 Kilo Bread requires 32 Kilo Wood. For second baking, 100 Kilo Bread requires 12 Kilo Wood. For third baking, 100 Kilo Bread requires 8 Kilo Wood. For fourth baking, 100 Kilo Bread requires 7.5 Kilo Wood. The crown is built as low as possible and raised 10 to 14 inches in center, sloping on both sides from 4 to 6 inches, above the hearth or sole. Further, the hearth of the genuine Vienna Oven also slopes from back to front. The object of this is to keep the steam from coming out of the mouth or oven door. (See Steam.) The author of this book has had some of these old style Vienna Ovens under his supervision, which were fired with natural gas. Two or three large gas pipes are run into the oven chamber extending about 18 inches into the oven, set at an angle towards the crown, with valves and air chamber on outside of the oven to the right of the oven door. When gas is turned on, long flames will stream along the crown of the oven chamber, diagonal towards the left rear wall Part 5 19 where the damper is located. After being fired from 2 to %y 2 hours steady, the arches should show a white, heat, and the hearth a bright red when gas is turned off. Being allowed to stand off for at least one hour, it is ready for baking. Steam being injected or water splashed in, these ovens bake especially nice milk or water rolls (hearth rolls.) After a few bakings, the gas is turned on again for from 15 to 30 minutes. The more popular style of direct fired oven, very efficient for general baking, bread, cake and pies has the furnace placed inside the baking chamber on one side of the door in front, the damper being on the op- posite side. After the fire is lit, the heat travels to the back of the chamber and then turns back to the flue to reach the chimney, or in more modern ovens, the heat chamber above the baking chamber. It is best to let oven rest awhile after damper is closed and fire cov- ered or drawn, to settle the heat. The advantage of this oven is, that you can cool it down and get up a flash heat again in short time, which is of special value where small batches of different kinds of baked stuff are wanted alternately, depending on one oven. The grate is set a few inches below the sole or hearth. Having no extra heat storage chamber, it is essential that the heat is allowed to linger longer in the oven, and a slow fire (or a larger fire banked) should be kept during the time there is no baking done. This style oven is built as a stationary brick oven or portable oven, the out side frame being metal, stand- ing on iron legs. *" INDIRECT OR FURNACE FIRED OVENS we call such ovens which have a furnace underneath the oven-chamber, fired from front, side or rear, the fire or heat traveling around and over the top of the baking chamber, adopted principally for Portable ovens or as in Shelf ovens, where stove pipes are run through the baking chamber from the stove or furnace under- neath. REEL and ROTARY also have a furnace be- low, but the heat strikes the baking chamber more 20 Part 5 directly, as the furnace is open on top or only partly arched over the top. REEL OVENS are used almost exclusively in Cracker bakeries, on account of the shelves or plates being so easily reached with the peel for rilling and emptying, but are also used in some large bread baker- ies for pan-bread. They are built on the principle of a Ferris Wheel. The baking blades are made of steel or sheet iron. ROTARY OVENS have only one baking surface revolving like a Merry-go-round. These ovens have a tile or soapstone hearth and are mostly used for pie baking. CONTINUOUS or HOT AIR CHAMBER OVENS are usually called Patent Brick Ovens and are the most popular for bread baking exclusively. The heat never strikes the baking chamber direct, being fired from the furnace below, either in front, side or back. The heat is accumulated and stored in chambers below and above the baking chamber, and no flame, smoke or dust can enter the same. The heat being stored, they are generally fired some hours before bak- ing is commenced, and can be used continuously. These ovens are preferred for baking bread and rolls exclusively on account of the heat being constant and uniform, but are not so practical for a general baking, including bread and cakes on account of the difference of heat required. When once the baking chamber is allowed to cool down, as needed for cakes it takes some time to get it hot enough again to bake bread. The baking chamber of the Continuous Ovens measures generally from 10 to 13 feet wide by 12 to 14 feet deep inside measurement. Of late, however, these ovens are built in much larger sizes with uride mouth or tiuo doors. The hearth is from 14 to 22 or even 25 feet across, by 13 to 14 feet deep. Although these new features were looked at by the bakers very sceptical and considered in diametrical opposition to all theories and traditions of oven building, they have Part 5 21 apparently given complete satisfaction so far. A great saving of fuel and labor, besides offering many con- veniences and better facilities for peeling and un- loading. HOT WATER OR STEAM PIPE OVENS are heated with a number of wrought iron pipes, located below and above the oven sole or drawplate. These pipes, are partly filled with water and hermetically sealed on both ends. The rear ends extend about a foot or less into the furnace which is usually at the rear of the oven. The furnace heat converts the water in the pipes into steam, and this steam being prevented from escaping, acquires a continually rising atmos- pheric pressure upon the water and a higher temper- ature is the result, which is transmitted from the pipes throughout the baking chamber. These pipes or tubes being first carefully tested as to their strength and flawless tightness, by exposing them to a consid- erable higher pressure than required for the baking heat, there is little danger of explosion. However, if in time any of the pipes should burst or swell, it is an easy matter to replace any single pipe with a new one, as they are not connected or dependent in any way on one another. The most popular Steam Pipe Ovens are the DRAWPLATE. The principle of these ovens which also accounts for the name, lies in the arrange- ment of the baking plates being removable from the oven chamber. The slower process of loading the oven with the peel, has led to the idea of building ovens with sliding plates, which can be withdrawn, loaded quickly, and running mechanically on wheels, pushed back into the oven. The objection to the extra space required, when plates are pulled out, has been greatly dispelled, with the construction of Double deckers, one on top of the other, practically taking only the space of a single decker, and reducing the cost of construc- tion as well as the cost for fuel and operating. TRAVELING or CHAIN OVENS have been in use in Europe for baking crackers and small sweet 22 Part 5 goods for some years, and in this country for Matzos. They are equipped with a steel wire netting or steel plates fastened to endless chains traveling through the baking chamber which can be from 30 to 60 feet long ; speed can be regulated, fast or slow. Attempts have been made lately to build this style oven for bread baking. The writer has had an opportunity to watch the baking process of the first oven of this kind built in America (in Montreal, Canada) and was very favor- ably impressed with the uniformity in baking, simplic- ity of mechanism and great reduction in oven help. The baking chamber in this oven is 50 feet long and 5 feet wide. The firing is done from a small tunnel built under the center of the oven where two furnaces are located, one running towards the rear, the other to- wards the front of the oven. It requires comparative- ly a small amount of fuel considering the amount of bread turned out in a day's baking, from 8,000 to 12, 000 loaves and its capacity is claimed to be far above that amount, being a continuous baker. FIRING. The proper firing of any bake oven depends on the construction of the flues and heat chambers, the kind of fuel and the draft of chimney, and differs greatly from firing a boiler or larger furnace. I have twice tried the experiment to put regular firemen in charge of firing the bake ovens. Both men claimed to be expert firemen ; one having fired on Railroad Locomotives, the other in a large power house. How- ever, both failed to make good ; they were so used to keeping on firing and poking and keeping up a lively fire, which we do not require for our Ovens. A well known baker remarked at a convention, "I am satisfied the fuel can be reduced twenty per cent or more, if it was handled with judgment, but it seems impossible to get laborers to use brains, they simply go on firing without using any judgment." Now, I never trust the firing of any oven to a cheap laborer, whether there is one oven or ten to be looked after. Part 5 33 When starting a new fire with coal or coke in a cold oven, you will have less smoke and less loss of heat by kindling the wood in the front part of the grate, throwing a few shovels full of fuel in the back part of furnace, to raise its temperature first to the igniting point before spreading it over the new fire, and vou will not smother the flames. When burning BITUMINOUS or Soft Coal, which as stated before contains large amounts of vol- atile or gaseous matter, I recommend the so-called caking system for firing. This means when charging the fire with fresh coal, the cool is piled in the front part of the furnace as close as possible to the door and left there from 10 to 15 minutes. As this coal is get- ting heated, the volatile matter (hydrocarbons) are driven off as vapor or gas making the coal carbonized or coked, and they will give more heat and make less smoke when later pushed back and distributed evenly over the fire, besides, these escaping gases while pass- ing over the fire in the rear, yield a good percentage of heat (8,000 to 12,000 B. T. U.) Although soft coal is considered cheaper than hard coal or coke, it re- quires more care and judgment as they will produce soot and smoke, clogging up the flues and chimney and leave more ashes to be removed. The loss of heat from these causes is often as high as 50 per cent. (See fuel, page 11.) Burning ANTHRACITE or HARD COAL, a smaller fire is required, especially in Patent Ovens. Don't smother the fire with piling too much fresh coal on top of it, especially if wet. (see fuel.) The smaller the size of the coal, the more you will choke or chill the fire and obstruct or prevent combustion, besides burn- ing out the grate bars, (see page 9) Percentage of ashes varies from 8 to 24 per cent in hard coal. When coal is wet, the coking system mentioned above will be found of great advantage. Firing hard coal in Draw- plate Ovens, I prefer Chestnut and Egg mixed. For direct firing Furnace Ovens, Egg Coal is the best size. 24 Part 5 For Reel and Rotary Ovens, larger sizes are prefer- able ; Egg or Stove or both mixed ; but I prefer coke in either oven. COKE, as stated before (see fuel) is composed of about 89 per cent pure carbon, or plainly speaking, gives 89 per cent heat and only about 10 per cent ashes. Many bakers make the mistake when burning coke, to start the fire too slow. The coke being honeycombed and leaving so much space for air to pass through, you should fill the furnace considerable more then with coal, and also pull the damper wide open, until there are no more dark spots to be seen in the fire. The arch as well as the coke must show almost a bright light red heat, which should take from 40 to 50 min. Then close the damper, leaving about one inch opening for the escape of the gases. After, say two hours from time of firing, you will notice no more flame or just the least bit of a bluish tongue of flame ; then you close damper down tight, and the heat will last from 10 to 12 hours. Coke fires never need much shaking of grate or poking of fire. When once you have a solid fire, the most that may be required, is to pull damper two or three inches after several hours for 15 or 20 min. To get a good solid heat from coke, let first firing burn up brisk, then shake down or poke a little, to settle; then fire the second time which will be sufficient to last for a day's baking. The most important rule to get best results from any kind of fuel in a Patent or Hot Air Chamber Oven is, to let fire draw brisk first, then close damper half until top arch and sides show bright red clear back to flues. This is what produces storage heat, because so long as the fire draws and the dampers are open, the heat will pass through the chambers rushing for the chimney. I can demonstrate the value of solid heat in a good Patent Continuous baking brick Oven best, from our own report of our average Friday's Baking (for Saturday) which means about forty-six thousand loaves. Our ten continous baking ovens which have Part 5 25 not been fired after ten o'clock Friday morning are almost continually used from one A. M. Friday to one A. M. Saturday, full 24 hours. No baking being done on Saturday, they stand idle, and instead of cooling off (with no fire in the furnace) the accumulated heat penetrates the oven chamber, and by Saturday we even open front oven door, (baking chamber) and smoke damper for several hours, to let the heat out and start baking Sunday morning with practically the heat left over from previous Friday. The fire started Saturday night will not have full effect until Sunday noon or at least 6-8 hours after being started. Just get the arch to white heat once in twenty-four hours, and you can bake bread continually. However, if such ovens must be cooled down for cakes, it is a matter of many hours to get the solid heat back again. Ovens used exclusively for Hearth Bread must have a good bottom heat to give the loaves a good spring, otherwise they run flat. Drawing so much heat continuously, a larger fire must necessarilly be kept in the furnace, but little or no extra draft is required, the object being to keep the heat lingering under the Oven chamber as much as possible. An occasional rest is of great benefit and the Thermometer or Pyro- meter will go up 20 to 30 degrees in a short time. IF MIXED BAKING, Bread, Cakes and Pies are to be done in one oven, the DIRECT FIRED brick or portable oven is very popular. As already explained (see ovens) grate is set a few inches below level of oven sole. I advise a banked fire to be kept all during time there is no baking, and giving it before baking is commenced a slow draft to allow the product of com- bustion, seen in long pale tongues, to spread and linger along the crown or top of oven chamber. There are several styles of modern PORTABLE OVENS with furnace below the baking chamber which turn out a large amount of well baked goods. It is to be specially recommended, to start a moderate fire at long as possible before baking time to get a more uniform, 26 Part 5 steady heat. Natural gas being used as fuel, I have always found it a fuel saver and heat preserver to pile some fire brick loosely in the fire box or furnace for the gas flames to pass around them. Judging Heat by Color. Temperature Fahrenheit. COLOR. Temperature Fahrenheit. COLOR. 900° Red (dull) 1900° Orange 1200 Red (dark) 2100 Yellow 1400 Red (cherry) 2300 White 1600 Red (bright) Over 2500 White (dazzling) Melting Point of Different Metals. Name. Degree F. Name. Degree F. Tin 446° Copper 1996° Lead 608 Glass 2377 Zinc 680 Iron (cast) 2450 Aluminum 1400 Steel 2500 Bronze 1692 Gold (pure) 2590 Silver 1873 Iron (wrought) 2912 Brass 1900 Platinum 3080 Part 5 27 DRAFT. Draft is a current of air, and as we have learned from chapter on combustion, air is the life of fire, and the briskness of the fire depends entirely on the proper amount of air supplied. Therefore, it is most impor- tant to have proper facilities to increase or decrease this current of air (Draft.) To control or regulate the draft, we need the draft door on the ash-pit (below the fire) and the damper in flues or chimney (above the fire.) They work in conjunction with each other. Either one worked alone will be a waste of heat or fuel. The draft door should be so arranged that it can be kept wide open, half open or nearly closed, or it must be perforated and supplied with a slide to reg- ulate the air supply. The size of furnace depends on kind of fuel used. Soft coal being lighter than hard coal, requires more area for the same amount (by weight) as hard coal. When burning coke, the grate can be set a few inches below the dead plate in front and the bridge in back of the grate, a larger amount of coke being fired at one time, than coal. This is especially to be considered in direct or inside fired ovens. The grates, most always made of cast iron, do not only hold the fuel, but also admit the air, and for that reason must have open spaces between the supports. At least half the grate surface must be air space, the other half (the bars) serving to hold the fuel. There are different styles of grates used by different Oven Manufacturers. The single bar grate is very popular; about 2^4 to 3 feet in length. The thickness of the lugs on both ends determine the width of the open spaces of the grate. These bars are more or less sloping (thinner) on the bottom, which gives a better air supply. Another style used more for very small coal (as in boilers), is the Herringbone. SHAKING GRATES are preferred by many bakers and used in most all portable ovens, and are especially an advantage where the square fire-box or round pot is set below the furnace proper. Another 28 Part 5 great advantage of a shaking grate, is because the furnace door can be kept closed while raking the fire, and no smoke or ashes will blow into the shop. The inrush of cold air over the fire through the open fur- nace door (the damper always being opened when shaking fires) is also avoided, which means preventing a loss of heat. The furnace door should also be perforated and have a slide, especially when coke or soft coal, rich in carbohydrates are burned, as in this way, some air can be admitted over the top of the fire to mix with the gases which linger on top of fire, causing com- bustion of same. The admission of steam or water under the grate or furnace does not produce more heat, as some bakers imagine. It is only of benefit when coal are used, which stick to the grate bars or clinker badly ; the steam coming from below will prevent this to some extent, keep the grate clear and also keep it from burning or melting. A better dis- tribution of air and more complete combustion is the result, which also means indirectly, a saving of fuel. But, care must be taken not to admit too much steam, and I recommend the safer method of keeping a basin of water in the ash-pit, or better still, to have the bottom ash-pit cemented, and a few inches lower than the floor, keeping a small pool of water in same. Glowing pieces of fuel dropping through the grate will create sufficient steam for this purpose. CHIMNEY AND FLUES. The chimney answers two purposes ; (1) to create a natural draft for the fire; (2) to carry off the ob- noxious gases of combustion and the smoke. The area and height of a chimney and the position of its top outlet to the surrounding buildings, has an im- portant bearing when erecting a chimney. Gases, hot air and smoke always ascend in a spiral column, which means, for instance, that a ten by ten-inch square chimney flue is no better or its practical work- Part 5 29 ing area no more extensive than a ten-inch round flue. There is also less friction in a round chimney flue than in a square one, because the spiral ascent of the draft moves more easily. The efficiency of the chimney (flue) depends on volume of passage due to area (size of flue) and velocity due to height of chimney. Therefore, the suction or speed alone do not make perfect draft; there must also be sufficient room to carry off the smoke. The chimney top should reach above the surrounding buildings if possible, as wind currents will rebound or be checked by walls or roofs in their way, and will force the air down into the chimney. It is also well known that there is quite a difference in draft of a chimney in summer or hot days and that produced in winter or cold days. On damp and murky days the draft is especially poor, and it is more difficult to get sufficient heat out of the fuel. The outside air passing over the top of chimney, say ranges between 40 and 85 degrees on an average, while the hot gases passing through the chimney average from 400 to 450 degrees. Bulk for bulk, the outside air has about twice the weight of the hot gases. In localities high above the sea level, where air is rarified or thinner, a larger volume of same must be supplied to get sufficient oxygen for combustion. The wind or air currents passing over the chim- ney, carry off the gases or hot air and smoke as they come from the furnace, also create a suction or draft. With a high wind blowing, the fuel will burn away more or less briskly, even if the draft door (ash-pit) is closed as long as damper in chimney or flue is wide or even only partly open. The inside area of a chim- ney should never be less than 9 or 10 inches if round, or 8 x 12 rectangular, or 10 x 10 square, or always be a little larger than the end of stove pipe or flue where it leads into the chimney. Never have the end of stove-pipe, bricks or casing of flue, etc., extend beyond the inside surface or wall of chimney, neither allow any crevices or leaks, as the least obstruction prevents 30 Part 5 the free passage of gas and smoke. The inside walls of chimney should be as smooth as possible. Some masons are very careless in this respect. The inside finish of a chimney is certainly of more importance than the outside, and every baker should watch the erection of any new chimney very carefully. Every oven should have its own chimney flue if possible, and no other flues or stove-pipes running into it. For a Two Oven chimney, it is best to allow a double area, and have a thin partition running up through the center. Sharp bends or offsets in the chimney will also reduce the area and choke the draft. If there is a soot pocket in the chimney below the point where the smoke-pipe or oven flue runs into the chimney, the same should never be deeper than one or two feet, and the slide or door of same must be kept closed perfectly tight. DAMPERS are checks or valves in or above the chimney, and control the draft. On Continuous Bak- ing and Portable Ovens, dampers usually have the shape of a slide, to be operated from front of oven, by a rod. On Draw-plate and Reel Ovens, the damp- ers generally consist of a drop door or lid, fitted over top of chimney, and are operated by a chain. The reason for the latter arrangement is, on Reel Ovens, especially used for crackers, there must be a constant flash heat and a quick draft and frequent manipulation of damper is necessary. On Draw-plate Ovens, the heating surface (see ovens) is so small, that the fire must be drawing nearly all the time, more or less, and the drop door on top of chimney is more efficient for the purpose. I would not recommend to have the inside area of chimney reduced toward the top, es- pecially when solid fuel is burned, coal or coke. Some bakers think by running the brick chimney only half way the required length, and putting a pipe on top, they save money. But alas, they have more annoy- ance from smoke or poor draft, and do not get the full heat value out of the fuel. Theoretically, anthra- Part 5 31 cite or hard coal requires more draft than soft coal, but on account of the latter having a greater propor- tion of gaseous products of combustion, the flue area must be larger for burning soft coal than for anthra- cite. The height of chimney does not matter materi- ally, but the difference in area of the flue required may be as high as 30 per cent, or a flue 8 x 12, good for hard coal fire, may have to be increased to 10 x 12 for soft coal. So, when changing from one coal to another, it is often well worth looking up the available chimney area. Coke requires a good draft, but burn- ing easily without smoke, the area of chimney can be limited without danger to draft. To clean out flues and chimney, I throw salt on the fire and open damper. Amount of salt depends upon area to be cleaned. The sulphurous gases eat the suds in a very short time. I use rock sa ^> f rom three to six pounds. STEAM. A certain amount of steam or moisture is required for the heat of the baking chamber during baking. The amount, of course, varies widely, and every baker knows that especially for Rye and Vienna Bread and Rolls, in fact anything baked direct on the Oven-hearth, a larger amount of steam is necessary, and the supply of steam must be replenished ; therefore, it is essen- tial that no steam can escape. In inside fired ovens, the direct fire leaves more or less moisture in the oven chamber. In smaller bakeries, with only one oven, perhaps a portable one, with no live steam supply, you may produce sufficient moisture by placing a pan of water near the fire-place and get it boiling. However, small boilers of sufficient capacity can now be bought so reasonable, that it will be a paying investment even for the small baker, as he can do all his cooking, pie filling, icings, mush, etc., in shorter time, and have a liberal supply of steam for proof boxes. Most Oven Builders also make it a point to supply steam or hot water boilers to their ovens on request. However, I prefer an independent boiler as a safer proposition, 32 Part 5 as you can raise or lower your steam supply or pres- sure at any time with very little fuel and in a few min- utes. For larger bakeries, of course, more steam and larger boilers are required. However, the pressure should not be over 30 lbs., and always carry plentv water in the boiler, at least 2 to 2^ gauges, to keep the steam moist. Dry steam or too much steam in oven is worse than not any at all. Some bakers think steam is steam, and always alike, and I have found it difficult to convince some of the old oven men that they can use too much steam. Of course, most ovens have a steam damper in the rear in the baking chamber, by which you can let surplus of flash heat and steam escape. Steam for Bakeovens is best at a pressure from 15 to 30 pounds and the boiler should never be allowed to be less than half to two thirds full of water, indi- cated on the water gauge. While drawing the steam from boiler, you will notice the gauge (indicating the pressure) drop rapidly. Therefore, you must keep up a good fire. For this reason you may have 30 pounds pressure at the start; it will then be easier to keep it from going below 15 pounds, which is called one Atmospheric pressure. Steam is like gas, expanding through application of heat. The temperature of steam increases with the amount of pressure (indicated on the gauge) as shown in the following table: Pound Pressure Temp, of Steam 212 degrees F. 5 227 degrees F. 10 239 degrees F. 20 259 degrees F. 30 274 degrees F. 40 286 degrees F. 50 300 degrees F. At about 320 degrees, F. steam is thoroughly "dry" and will just do the opposite to your bread, from what it is expected to do. Part 5 33 It will cause it to be "blind," "shrink" the loaves or it will even "char" the crust. Now as the tempera- ture of the Oven is about 450 degr. F., and on account of steam expanding with increase of heat, the oven will be full of superheated steam, when forcing it in quickly. "Through steam" or superheated is prac- tically invisible. What you see issuing from the spout of a closed tea-kettle, is condensed steam and visible as vapor. The lower temperature of surrounding at- mosphere chills or condenses the steam and naturally in cold weather you can see steam much plainer than in warm weather. You can notice that on your own breath. The only true steam issuing from the spout of a kettle or any other closed receptacle, (valve of a steam boiler, etc.) is contained only in the small space immediately in front or on top of the point, where it issues into the atmosphere. You can notice this empty space very plain wherever steam escapes. Steam will always look for an outlet but does not descend below the highest point of exit, for in- stance, the oven door. For this reason, Vienna or Rye Bread Ovens are built sloping from back to front and the front door provided with a tin slide which can be lowered while peeling in Vienna or Rye Bread, to pre- vent the steam from escaping through oven door. A strong kettle or pot with tight cover and spout is preferable. A very simple arrangement for any oven is to run a one inch pipe over the fireplace or if oven is fired from below, run pipe along the inside wall, of oven chamber; the pipe is connected with the cold water and is perforated. The pipe takes on about the same heat as the oven chamber and when you turn on a little cold water it will instantly turn into steam and spread through the oven. OVEN RECORDS. Every baker, no matter how small or how large his business should keep occasionally a record of a whole day's baking of one or more ovens, marking down the heat variations, fuel consumed, amount of 34 Part 5 baking turned out, time oven is fired, etc. I refer to my own Oven Record Cards, samples of which I re- produce herewith (filled out). With these cards I was able to cut down the fuel gradually to less than one half the amount previously used. My fireman knows the character of every one of our ten ovens exactly, how much fuel every one requires, how often to fire, when to close dampers, etc., of course in our bakery the heat recording is much simplified as our Ovens are equipped with Electric Pyrometers, all oper- ated from one switch-board and all recording the exact heat of each oven. I find that 450 degrees F. is the proper heat to start Bread Baking. I give here a record of the variations indicated on the "dial" of the switch-board for each oven, at different hours during one day's baking. Re< :ord of Heat Variations. Fuel No. Oven TIME AND DEGREES OF HEAT. 11 P.M. 2 A.M. 450 6 A.M. 10A.M. 4P.M. 8 P.M. Coke 1. 435 430 420 430 435 Coke 2.X 440 445 395 390 405 435 Coal 3. 450 460 430 415 430 440 Coal 4.X 435 450 400 385 405 425 Coke 5.X 440 455 395 395 390 430 Coal 6.X 450 460 405 395 420 415 Coal 7. X 445 455 400 390 395 420 Coke 8. 450 450 440 435 430 445 9. Oven in Re pair Coal 10. 440 440 445 445 430 435 Ovens marked X are used for Hearth bread, which accounts for the drop in temperature. Firing started at 11 P. M., Baking started at about 3 A. M. Part 5 35 OVEN REPORT. BRAUNS " PRACTICAL" SYSTEM^- Oven No._ ,£ Pate "/* f/ii. Ma Z1A 3AA MA L2A L.&L UL HI- If-t- MA Ilh. l£A ZIP ilh UA SU3 LA &k HA IduadL Ul 1L La SA lA £JL LA HA & NAME fftrmt/rna/lt C/rttk 42A U4/UA/cMjm n Urtth X It /JJ£ M® •UumaXaj, M. urWc, 4ML- h/ T MynlswjMU Cfrfc&L /a<4A y^i IAl o-cisVK Time IN aw- r££ Time OUT £* 5& klk ft* 00 vam m* ro /A. £HZ &g SJ± ?0 7 \1L at £M 631 Degree* HEAT uk %lL\ Time FIRED 2,0 UA ask IL 3f ¥JM 41 / $jr ZH 2J ^J^ z* 6Jz vt 7 zX n± UAA zjth HAS. VAA Hit i/JA HAL XlA , O HkA U. s* Amount mM AA& A.M. LlL£AJL> abo U> MA* I 1911 36 Part 5 c0^vcuirj rUtgtt- OVEN REPORT. BRAUN'S "PRACTiCAL" SYSTEM. uJJL&l Oven No, / 3jH<