-1 ; TS 1109 .H77 | Copy 1 DEPARTMENT OF COMMERCE Technologic Papers OF THE Bureau of Standards S. W. STRATTON, Direotor No. 187 a study of test methods for the purpose of developing standard specifications for paper bags for cement and lime BY PAUL L. HOUSTON, Associate Physicist Bureau, of Standards MARCH 21, 1921 -7- Is 1 6 PRICE; 5 CENTS Sold only by the Superintendent o( Documents, Government Printing Office Washington. D. C. WASHINGTON . GOVERNMENTi'PRINTING OFFICB 1921 DEPARTMENT OF COMMERCE Technologic Papers OF THE Bureau of Standards S. W. STRATTON, Director No. 187 A STUDY OF TEST METHODS FOR THE PURPOSE OF DEVELOPING STANDARD SPECIFICATIONS FOR PAPER BAGS FOR CEMENT AND LIME BY PAUL L. HOUSTON, Associate Physicist Bureau of Standards MARCH 21, 1921 PRICE. 5 CENTS Sold only by the Superintendent of Documents, Government Printing Office Washington, D. C. WASHINGTON GOVERNMENT PRINTING OFFICE 1921 fl 1^ II n II llllWHIHilil 1IHMIJ ii LIBRARY OF CONGRESS pfOEIVEb APR 851921 DoeyMENTs c aiON II-IU3C A STUDY OF TEST METHODS FOR THE PURPOSE OF DEVELOPING STANDARD SPECIFICATIONS FOR PAPER BAGS FOR CEMENT AND LIME By Paul L. Houston ABSTRACT This technologic paper contains information relating to the methods of testing and the apparatus employed in determining the quality of paper bags for lime and cement. A brief description is given of the ordinary tests performed on paper, such as weight in pounds of the standard size ream 2 5 X40— 500, bursting strength in points, tensile strength in kilograms, stretch in centimeters, folding endurance in number of double folds, percentage of fiber composition, percentage of ash, and percentage of rosin sizing. A special test is developed for giving numerically the stresses and strains that the paper of these bags undergo in service. This test is called a resiliency or endurance test. A service test is also given to determine the breaking strength of the paper when the bags are filled and dropped. A comparison is made of the results of this test with the results of the above resiliency test. Another service test is devel- oped for determinining the strength of the adhesives used in these bags. The results of all these tests are tabulated, and from these data the very best quality bags are chosen. In the conclusions, special consideration is given this choice of best bags in deter- mining the characteristics of a good quality bag, and specifications are drawn up accordingly. CONTENTS Page I. Introduction 3 1. Purpose of tests 3 2 . Discussion of materials and apparatus used 4 3. Scope of the tests and methods employed 6 II. Experimental work 7 1. Physical and chemical tests 7 2. Tables of results 8 3. Diagrams illustrating results n III. Conclusions 18 IV. Specification 18 I. INTRODUCTION 1. PURPOSE OF TESTS The purpose of these tests is to aid the paper-bag manuf acturers to meet the requirements of the lime and cement manufacturers in obtaining a suitable paper bag in which to ship their product. For a number of years the paper-bag manufacturers have attempted to manufacture such an article to substitute for the cotton bag 3 4 Technologic Papers of the Bureau of Standards that had hitherto been used with great expense to the lime and cement industries because of the high price of cotton. The success of the paper-bag industry in this undertaking has been varied. A few of the consumers have given favorable reports on the use of their product, while others have claimed the bags fail in service. A number of consumers claim the glue gives way easily if the bags are held in storage any length of time. Since the bag manufacturers have been unable to derive any decided benefit from the above reports of the consumers, the present study was undertaken in order to develop specifications for these paper bags. 2. DISCUSSION OF MATERIALS AND APPARATUS USED The materials used for this study were representative samples of paper bags obtained from a number of the leading bag manu- facturers. The bags were given the following identification numbers: 14373, H374. 14375. 14376, H377. H378, H379, 14380, and 1 438 1. The apparatus used was the Mullen paper tester, the paper scales, the 200 kg tensile-strength instrument, the 50 kg tensile-strength instrument, the folding endurance machine, microscope, glass slides, test tubes, extraction flasks, siphon cups, evaporating dishes and crucibles, all of which are used for ordinary physical and chemical tests. Descriptions and photo- graphs of these instruments and apparatus may be obtained from circular of the Bureau of Standards No. 107, with the exception of the large 200 kg tensile-strength machine. The description and photograph of the tensile-strength apparatus in the above circular apply to the small 50 kg instrument. However, the 200 kg and the 50 kg instruments are practically identical in construction, the 200 kg machine being used for any material breaking at or under a load of 200 kg, the 50 kg machine for material breaking at or under a 50 kg load. In addition to the above paper-testing instru- ments a wooden platform with trapdoor and an ordinary foundry jolter were used for service tests. The wooden platform was built 3 feet high and allowed a bag filled with sand to be dropped through its trapdoor onto a solid wooden stand. The jolter con- sisted of a solid iron plate 3 inches thick which could be raised and lowered in rapid succession by means of air pressure. This machine, of course, was constructed with the necessary intake and outlet valves, air chamber, and piston to allow for the continuous jolting movement of the plate. For the purpose of developing a laboratory test that would give numerically the resiliency of bag Testing Paper Bags for Cement and Lime 5 paper or the stress and strain that the paper of a bag undergoes in service and by which the results of the above service tests could be checked, the large 200 kg tensile-strength machine was adopted with the following additional attachments : A brass cylinder was constructed and fastened to the upright standard in such a way that it would revolve. The revolution of this cylinder was controlled by a small wire over a pulley from the weighted pendu- lum so that, as the pendulum moved from its vertical position due to the increasing loads, the cylinder revolved accordingly. This cylinder held a paper chart, and a glass recording pen was used to record both load and stretch. The pen was controlled by a small wire extending from the lower-jawed arm over a pulley in such a way that, as the lower jaw descended and the paper stretched under the load, the pen ascended and described a curve which registered stretch. It can thus be seen that the revolution of the cylinder caused the registering of load on the chart, while the ascension of the pen caused the registering of stretch. The result was a curve on the chart giving both the increasing load and increasing stretch until the paper broke. In order to read this curve it was necessary to draw up the chart so that load and stretch could be read at a glance. The method used was as follows: An ordinary blank piece of writing paper was used for this purpose and placed in position on the cylinder. A point on the paper was chosen as the zero point for load and stretch. Then the zero line for stretch was found by using a piece of steel between the jaws and by applying the various loads. Steel was used for this purpose because the chart was to be drawn up for a 70 kg load as a maximum, and steel would not stretch at this load. By this method the zero line for stretch was drawn with the record- ing pen from the zero point, and each kilogram load as indicated by the scale was pointed off as the load increased. At each kilo- gram point a line was drawn parallel to the base or zero line for load. This base line was found by operating the machine with nothing between the jaws and was drawn with the recording pen from the zero point. Each centimeter that the lower jaw de- scended from its starting position or zero point represented stretch and was pointed off accordingly. At the different centimeter points lines were drawn parallel to the zero line for stretch. In this way the chart was plotted to give accurately the stretch at different loads foi any paper breaking under a 70 kg load. 6 Technologic Papers of the Bureau of Standards 3. SCOPE OF THE TESTS AND METHODS EMPLOYED The object of these tests was, first, to discover all the physical and chemical properties of the paper of the bags; second, to check these results with the results of service tests on the bags themselves; third, to choose by the process of elimination the best bags of the series ; and fourth, to develop specifications from this choice of best bags. For the ordinary physical and chemical tests the methods employed have been fully described in Circular of the Bureau of Standards No. 107, with the exception of the tensile strength and stretch tests. For these tests, the 200 kg instrument was used, and test samples were cut 1% cm wide and long enough to allow 20 cm between jaws. In addition to the above tests a wet tensile test was conducted in the same manner as the dry tensile test described in the above Circular, with the following exceptions : The weight was removed from the pendulum of the 50 kg tensile-strength instrument, the machine was calibrated to find the corrections for the scale readings, and the paper was immersed for 10 minutes in water before testing. In both service tests bags were filled with 94 pounds of sand and then dropped or jolted until they broke open. In the jolter test the bags were jolted 1 inch high and 170 times per minute. An average of five tests was taken in each of these service tests to determine the strength of the bag. The method used for obtaining the resiliency of paper on the tensile-strength machine with its recording device was the following: In order to obtain curves or loops (as they should be called in this case) to show this resiliency or the endur- ance of paper tmder the repeated application of load, a load was taken in each case 10 per cent below the breaking point. This, of course, necessitated finding the tensile strength or breaking point for each grade of bag paper in both machine and cross direction. In order to do this an average of 10 tensile-strength tests was ob- tained. After obtaining in each case the desired load of 10 per cent below breaking point, each test sample was given this load, and then the load was released and the operation repeated until the test sample broke. All test samples for this work were cut nyi cm wide and long enough to allow 20 cm of paper between jaws. Three test samples from each grade of paper, cut in both machine and cross direction, were used in order to obtain an average, and data were collected accordingly. Testing Paper Bags for Cement and Lime 7 II. EXPERIMENTAL WORK 1. PHYSICAL AND CHEMICAL TESTS Each sample of bag paper was given the ordinary physical and chemical tests, such as weight in pounds of the standard size ream 25X40 — 500, bursting strength in points, tensile strength in kilograms, stretch in centimeters, folding endurance in number of double folds, fiber composition in per cent, per cent of ash, and per cent of rosin sizing. From these tests the ratio in per cent of bursting strength to weight in pounds of the standard size ream, 25 X 40 — 500, and the breaking length in yards were obtained as the best means for comparing papers of the same grade. An explanation and description of this ratio and breaking length may be procured from Circular of the Bureau of Standards No. 107. The results of these tests are compiled in Tables 1,2, and 4. In addition to the above tests the paper and bags were given the following special physical tests: The paper was tested for tensile strength in grams when it was wet, and was tested also for resili- ency or endurance. The numerical results are shown in Tables 2, 3, and 4 and are presented graphically in Figs. '1 to 54. The bags were tested for breaking strength by determining the number of times each bag could be dropped before failure, as shown in Table 5, and for strength of adhesive by determining the length of time each bag could be jolted before failure, as shown in Table 6. The purposes of these special tests were the following: The wet tensile- strength test was made in order to indicate what the strength of the paper of the bags would be when they became wet in shipment. The stress-strain or resiliency test was made in order to obtain a series of loops for each test sample, giving first the stretch at applied load, second the stretch when load was released, third the increase in stretch for every time load was applied over the previous time, and fourth the number of times the paper could stand the strain of this load before it broke. The purpose of the drop test was to reproduce service conditions, because a bag is often dropped while being handled. On the other hand, the jolter test not only tested the strength of the adhesive used in the bags but also somewhat duplicated the treatment that a bag undergoes while being jolted and jarred in shipment from manu- facturer to consumer. The following data were collected accord- ingly from all the above tests, and from these data it was not hard, by process of elimination, to choose the live bag papers which showed the best bursting strength, tensile strength, stretch, 8 Technologic Papers of the Bureau of Standards folding endurance and resiliency, and which as bags showed the best breaking strength and possessed the strongest adhesive. At a glance, bag papers numbered 14373, 14374, 14378, 14379, an d 1 43 8 1 seem to be the strongest. In comparing the following results of the resiliency test with those results of the drop test, it will be noted that the above papers proved strongest in both cases. This proves that the resiliency test is a very good test for showing what the paper of a bag will do in actual service, and since it is strictly a laboratory test, it is highly to be recommended . 2. TABLES OF RESULTS TABLE 1. — Results of Ordinary Physical and Chemical Tests on Cement and Lime Bag Paper Bag-paper identification numbers Weight of the standard size ream 25X40-500 Bursting strength in points Ratio of bursting strength to weight of the standard size ream 25X40-500 Percentage fiber composition Ash Rosin sizing 14373 14374 14375 14376 14377 14378 14379 14380 14381 Pounds 150 119 143 127 115 176 142 172 181 134.0 100.0 108.0 96.0 78.0 132.0 143.0 159.0 155.0 Per cent 89.3 84.0 75.6 75.6 67.8 75.0 107.0 92.4 85.7 100 jute and manila do 95 jute and manila, 5 chemical wood. . . 100 chemical wood 100 jute and manila 50 jute and manila, 50 chemical wood. . 75 jute and manila, 25 chemical wood. . 100 chemical wood do Per cent 4.10 3.60 4.70 3.30 4.60 2.30 2.00 1.27 .97 Per cent 3.40 3.80 4.90 3.30 4.10 4.40 3.90 .97 1.35 TABLE 2.— Results of Tensile-Strength Tests and Stress-Strain or Resiliency Tests on Cement and Lims Bag Paper Bag-paper identifica- tion num- bers Weight of the stand- ard size ream 25X40— 500 Load at breaking point Stretch at breaking point Breaking length Load 10 per cent below breaking point Number of times load is applied Ma- chine direc- tion Cross direc- tion Ma- chine direc- tion Cross direc- tion Ma- chine direc- tion Cross direc- tion Ma- chine direc- tion Cross direc- tion Ma- chine direc- tion Cross direc- tion 14373 14374 14375 14376 14377 14378 14379 14380 14381 Pounds 150 119 143 127 115 176 142 172 181 kg 35.0 28.0 27.0 26.5 21.5 46.5 37.5 43.4 42.3 kg 17.5 16.5 11.0 13.0 8.8 18.0 17.5 16.4 18.4 cm 0.57 .64 .49 .60 .30 .54 .64 .45 .50 cm 1.57 1.60 1.25 1.43 .70 1.34 1.06 1.12 1.14 Yards 7130 7160 5770 6380 5710 5100 8060 7730 7160 Yards 3565 4240 2350 3140 2340 3120 3770 2910 3110 kg 31. 5Q 25.20 24.30 23.85 19.35 41.85 33.75 39.06 38.07 kg 15.75 14.85 9.90 11.70 7.92 16.20 15.75 14.76 16.56 5.66 21.66 30.30 26.00 11.00 49.66 12.00 1.00 59.00 8. '66 12.33 19.33 8.66 11.66 4.66 9.66 2.00 9.66 Testing Paper Bags for Cement and Lime TABLE 3. — Results of Stress-Strain or Resiliency Tests on Cement and Lime Bag Paper, Showing Different Stretches Loop 1 Loop 3 Loop 5 Loop 10 Loop 20 Loop 30 Loop 40 Loop 60 Bag identification No. 14373: Stretch at applied load — do 1.68 5.66 .25 .90 2.60 6.28 .30 .94 1.18 3.85 .27 .53 1.75 5.23 .31 .80 1.16 2.90 .23 .40 1.68 5.46 .26 .82 2.31 4.93 .38 .80 2.10 3.13 2.01 5.77 .36 .91 2.30 .40 1.03 6.10 Stretch when load Is released — do.... do do.... 1.05 2.65 7.80 .47 1.44 1.90 Bag identification No. 14374: Stretch at applied load — 2.75 2.95 3.15 6.96 1.27 5.13 .86 5.90 .38 .99 3.75 .67 7.56 .42 1.34 1.56 Stretch when load is released — .51 .54 .56 Bag identification No. 14375: Stretch at applied load — do.... ..centimeters.. do.... do.... do.... percent.. 2.22 5.40 .50 .92 2.75 6.60 .60 2.60 5.60 Stretch when load is released— .36 .44 1.00 Bag identification No. 14376: Stretch at applied load — 2.16 6.50 .44 1.65 .36 2.51 .51 1.02 2.00 4.05 .43 .70 1.90 Stretch when load is released — Bag identification No. 14377: Stretch at applied load- 4.30 Stretch when load is released — centimeters.. do.... do.... .75 Bag identification No. 14378: Stretch at applied load- 6.38 1.06 5.28 .50 .95 7.12 .32 1.20 2.55 5.45 .58 1.00 Stretch when load is released — .40 Bag identification No. 14379: Stretch at applied load — do.... do.... 2.85 5.60 .64 1.05 3.10 6.00 .70 Stretch when load is released— Bag identification No. 14380: Stretch at applied load- 3.60 Stretch when load is released — do.... do .50 1.53 3.13 .32 .44 .78 3.90 .56 Bag identification No. 14381: Stretch at applied load- 1.83 4.50 .42 .66 2.10 4.95 .49 .72 2.33 Stretch when load is released — do.... .54 33325°— 21 2 IO Technologic Papers of the Bureau of Standards TABLE 4.— Results of Wet Tensile Tests and Folding Endurance Tests on Cement and Lime Bag Paper Bag-paper Identification numbers Wet tensile strength Breaking length Folding endurance in number of double folds Machine direction Cross direction Machine Cross direction direction Machine direction Cross direction 14373 kg 1.38 2.36 1.43 2.05 1.17 3.15 1.31 .80 1.26 kg 1.40 1.71 1.29 1.68 .92 1.35 .71 .30 .69 Yards 476 1026 519 836 525 926 349 243 362 Yards 482 746 468 685 418 396 262 90 199 10 000+ 10 000+ 10 000+ 6 220 10 000+ 10 000+ 10 000+ 7 244 10 000+ 10 000+ 14374 10 000+ 14375 1 998 14376 4 260 14377 5 011 14378 10 000+ 14379 10 000+ 10 000+ 10 000+ TABLE 5. — Results of Drop Service Tests on Cement and Lime Bag Paper Bag-paper identification numbers Position of bag when dropped Number of drops before failure Extent of failure On side and seam up do 2 3 1 1 1 4 4 1 3 Paper failed at seam. Do. 14374 14375 do Paper and glue failed at seam. Paper failed across edge, and glue failed at end. Paper and glue failed at seam, and paper failed across bottom side. Paper failed at seam. Do. 14376 do 14377 do 14378 do 14379 do 14380 do 14381 .. do failed at end. TABLE 6. — Results of Jolter Service Tests on Cement and Lime Bag Paper Bag-paper identification numbers Position of bag when jolted Minutes jolted before failure Extent of failure 14373 On side and seam up do 24 60 1 18 6 40 30 2 3 14374 . 14375 ... do 14376 do Do. 14377 do Do. 14378 do Do. 14379 . . .. ..do Do. 14380 .. ..do Do. 14381 do Do. Testing Paper Bags for Cement and Lime II 3. DIAGRAMS ILLUSTRATING RESULTS toopflt FlGS. i to 6. — Diagrams showing resiliency or endurance of cement and lime bag paper in ike machine and cross directions 12 Technologic Papers of the Bureau of Standards Figs. 7 to 14. — Diagrams showing resiliency or endurance of cement and lime bag paper in the machine and cross directions Testing Paper Bags for Cement and Lime 13 F13. 31 BpocIdob Dimensions: 3 1/3 X 30 CenUao&ssa, FlGS. 13 to 22. — Diagrams showing resiliency or endurance of cement and lime bag paper In the machine and cross directions 14 Technologic Papers of the Bureau of Standards Figs. 23 to 30. — Diagrams showing resiliency or endurance of cement and lime bag paper in Hie machine and cross directions Testing Paper Bags for Cement and Lime 15 pig. 37 Halt: 14379 - Maohl-OT SpeolQQD Dimeiioicne: 2 1/3 X SO oentimsserp loops 1.1 - 5 - 6 — 10 - 39 FIGS. 31 to 38.— Diagrams showing resiliency or endurance of cement and lime bag pape in the machine and cross directions i6 Technologic Papers of the Bureau of Standards Mark: 14330 - MftoMno.^-tl^ BpoolEan Dlaanelons: .3 1/3 K 20 Caatlaotar* Figs. 39 to 46. — Diagrams showing resiliency or endurance of cement and lime bag pape in the machine and cross directions Testing Paper Bags for Cement anal Lime 17 Figs. 47 to 54.— Diagrams showing resiliency or endurance of cement and. lime in the machine and cross directions 1 8 Technologic Papers of the Bureau of Standards III. CONCLUSIONS Conclusions to be drawn from the above results of tests, taking into special consideration the various tests on the chosen five best bags, are that a satisfactory cement or lime bag paper should have a very good bursting strength and a high tensile strength and stretch in both directions. It must also have a high endurance or resiliency, which is determined by the simple drop service test or by the better stress-strain laboratory test. A suitable bag paper must also show a good tensile strength when wet and must have a high folding endurance. As the above data show, it is not necessary to manufacture a bag out of very heavy paper in order to obtain a bag of the very best quality. For instance, bag paper numbered 14374 weighs only 119 pounds to the standard size ream 25X40 — 500, and yet is one of the five best papers tested. The fiber composition of a good bag paper should be not less than 50 per cent strong manila and jute and the remainder chemical wood. The ash should not be over 3 per cent and the rosin sizing should be at least 3.5 per cent. IV. SPECIFICATION In writing up the specification for cement and lime paper bags it does not seem wise to recommend any specific weight of paper, since this study shows that weight alone should not be considered in choosing the best-quality bags. It is for the consumer to decide what weight bag he wishes to use and for the manufacturer to decide what weight bag paper he wishes to manufacture. However, it is thought that both manufacturer and consumer would prefer a light-weight paper for reasons of economy. For these reasons weight is not given in the following specification, but in all other respects it is thought that this specification will meet au requirements and can be adhered to by the manufacurers without any difficulty, and that bags made of paper that conforms to this specification will prove satisfactory to the cement and lime manufacturers . SPECIFICATIONS FOR PAPER BAGS FOR CEMENT AND LIME Bursting strength: Not less than 100 points. Ratio bursting strength to weight in pounds of the standard- size ream, 25 X40 — 500: Not less than 75 per cent. Fiber composition: Not less than 50 per cent manila and jute; the remainder as chemical wood. Testing Paper Bags for Cement and Lime 19 Ash: Not over 3 per cent. Rosin: Not less than 3.5 per cent. Tensile strength (test sample 2% cm wide and 20 cm between jaws): Not less than 28 kg (machine direction), 16 kg (cross direction) . Breaking length : Not less than 7000 yards (machine direction) , 3500 yards (cross direction). Wet tensile strength (test sample 15 mm wide and 90 mm be- tween jaws): Not less than 2000 g (machine direction), 1300 g (cross direction) . Wet breaking length: Not less than 800 yards (machine direc- tion), 400 yards (cross direction). Folding endurance (test sample 15 mm wide and 90 mm be- tween jaws): Not less than 10 000 double folds (machine direc- tion), 10 000 double folds (cross direction). Resiliency strength (test sample 2% cm wide and 20 cm be- tween jaws): Not less than 20 times (machine direction), 9 times (cross direction) . Breaking strength of bags: Not less than 3 times. Adhesive strength: Not less than 30 minutes. Washington, September 20, 1920. LIBRARY OF CONGRESS 015 992 289 3