Digitized by the Internet Archive in 2007 with funding from IVIicrosoft Corporation http://www.archive.org/details/examinationofpapOOunitrich / C9V \? ^ f. Mail Lib. Agric. Vcpt. ^,,> 0^' Issued April 12, United States Department of Agriculture, BUREAU OF CHEMISTRY— Circular No. 34. H. W. WILEY, Chief of Bureau. EXAMINATION OF PAPERS. INTRODTJCTION. For the past five years the Bureau of Chemistry has examined and tested papers for the various Departments of the Government service, and since the estabhshment of the Leather and Paper Laboratory it has conducted investigations looking to the improvement of papers and the utiHzation of farm products in their manufacture. The Bureau has now the equipment and experience for conducting this work on a large scale. The work so far done has shown that the papers supplied for Government use too frequently fall below the specifica- tions, lack durability, or in some way are not adapted to the purpose for which they are intended. Valuable documents and scientific work are recorded on papers which will rapidly deteriorate, thus rendering the records useless. In this circular the methods and tests by which the composition and value of paper are judged, examples illustrative of the nature and interpretation of results, and brief outlines of the characteristics which the more important classes of paper should possess are given. Under statutory authority the Bureau makes tests for any branch of the Federal service, wherever located, and will also prepare, or assist in the preparation of, specifications which are accurately descriptive of papers suited to any given purpose for any branch of the Federal Government. H. W. Wiley, CIdef. Approved : James Wilson, Secretary. Washington, D. C, March 12, 1907. 27646— No. 34—07 -; NATTTRE OF EXAMINATIONS MADE. It is rarely necessary to make all the tests given in the following list, as usually a few determinations will definitely show the value of a sample for a given purpose. The nature and extent of the exami- nation to be made can only be determined after the receipt of the sample and of a full statement from the sender as to the object of the examination — that is, whether the value of the paper for a given pur- pose is to be determined or its agreement or disagreement with certain specifications is to be established. At present the Leather and Paper Laboratory and the Micro- chemical Laboratory are equipped to make the following physical and chemical tests, classified as quantitative and qualitative: QUANTITATIVE TESTS. (1) Kind of fibers or stock, i. e., rag, esparto, spruce, ground wood, etc. (2) Quantity of each kind of fibers or stock as per cent of rag, of spruce, of manila, etc. (3) Average length of fiber. (4) Weight per square meter or per ream. (5) Thickness. (6) Mean breaking weight. (7) Mean breaking length. (8) Loss of strength on folding. (9) Mean stretch. (10) Loss of stretch on folding. (11) Transparency. (12) Moistiu*e and ash. (13) Absorptive power of blotting paper. QUALITATIVE CHEMICAL TESTS. (1) Kind of sizing. (2) Character of sizing. (3) Kind of loading. (4) Reaction. (5) Bleaching agents. (6) Chlorids and sulphates. • DESCRIPTION OF QUANTITATIVE TESTS. Inasmuch as strength varies with the direction of the paper, tests are made on strips cut both lengthwise and across the sheet. The average of these tests gives the "mean" mentioned in the following descriptions. All of the strength tests are based on an atmospheric [Cir.34] 4 humidity of 65 per cent. When so desired strength is reported as pounds per square inch, as determined by the standard American testing machines, no correction being made in this case for variation due to the moisture content of the air, as these machines give only approximate results. Unless otherwise requested, weight, thickness, and strength will be expressed in the metric S3^stem. (1) Kind of fibers or stock is determined by microscopical exami- nation. ( 2) Quantity of each Mnd of fiber or stock is determined microscopic- ally by a count of the fibers of the different materials present, and will be expressed as "percentage by count" on the basis of the stock. The Bureau is not yet ready to say how close this ''percentage by count" will agree with ''percentage by weight," but there is every evidence that the error, if any, is not greater than obtains in the man- ufacture of paper. The actual percentage of stock in a paper is found by substracting the sum of the moisture, ash, sizing, and color- ing from 100. As the determinations of sizing and color are not usually made, the percentage of stock in all such cases can only be approxi- mated. (3) Average length of fibers is determined by microscopical meas- urements and is expressed in millimeters. (4) Weight is expressed in grams per square meter, or, when so requested, in pounds per standard ream (24 by 36 inches). (5) Thickness is expressed in millimeters, or, when so requested, in thousandths of an inch. (6) Mean breaking weight is the average weight in kilograms (1 kilogram = 2.2046 pounds) required to break a strip of air-dry paper 15 mm wide and 180 mm long (0.5905 inch wide and 7.087 inches long). (7) Mean breaking length is the mean length of moisture-free paper expressed in meters (1 meter = 3.2808 feet) which if suspended by one end would break of its own weight. (8) Loss of strength on folding is the decrease in strength caused by folding the paper a stated number of times under a uniform load of 7 kilograms, and is expressed as percentage on the basis of the mean strength. (9) Mean stretch is the elongation before breaking of the paper when subjected to a pull sufficient to break it, and is expressed in percentage. (10) Loss of stretch on folding is the decrease in stretch due to fold- ing the paper a stated number of times under a uniform load of 7 kilograms, and is expressed on the basis of the mean stretch. [Cir.34] (11) Transparency is penetrability to light and is expressed as the thickness of the paper through which a standard flame can be barely distinguished. (12) Moisture and ash are expressed as percentage on the basis of the air-dry paper. Loading as distinguished from the normal min- eral content of the paper and that added in the sizing and coloring can not be definitely determined, but may be approximated for dif- ferent kinds of paper. At present no corrections will be made for the loss on ignition of water of constitution or hydration present in China clay or other loadings, but the practice of the Bureau may be changed at any time on this point. (13) Absorptive power of blotting paper is shown by the height in millimeters to which water will be drawn in ten minutes' time by a strip of the paper 15 mm broad. QUALITATIVE TESTS. (1) Kind of sizing includes a statement as to whether rosin, animal sizing, starch, or casein (as far as the latter can be differentiated from animal sizing) has been employed. (2) Character of sizing refers to the resistance of the sizing and for the present is reported as '^ excellent," ''good," ''poor," and "very poor." (3) Kind of loading is reported as clay (kaolin), pearl hardening (sulphate of lime), agalite, barytes (blanc fixe or permanent white), silicate of soda, etc. (See also "12. Moisture and Ash.") (4) The reaction of a paper may be alkaline, neutral, or acid, and papers are reported as alkaline, neutral, faintly acid, and strongly acid. (5) Bleaching agents when present will be reported. (6) Chlorids and sulphates are reported at present as "trace," "low," "medium," and "high." SOME TYPICAL PAPER TESTS. The accompanying tables are illustrative of the two principal phases of paper tests, i. e., those whose purpose is to determine whether or not the papers delivered comply with the specifications, and those to establish suitability for a given purpose. Some tests made in this Bureau on papers delivered on contract to one of the Federal Departments are reported in Table I, and show the salutary effect on the quality of the goods which was produced by the institution of such examinations. ICir.34l 6 Table I . Composition of papers delivered on contract before and after institution of tests, as compared with (he specifications. Speclflcjations (stock). Composition of papers de- livered before tests were instituted. Composition cf papers delivered after tests were instituted. Sample. Rag. Wood pulp. Rag. Wood pulp. Soda process. Sulphite process. Soda process. Sulphite process. No. 1 ... . Per cent. Rag, 100 Per cent. 60.5 55.0 55.0 59.0 a 18.0 Per cent. 26.5 30.0 28.0 28.0 6 40.0 Per cent. 13.0 15.0 16.0 13.0 42.0 Per cent. 100 100 75 74 All manila. Per cent. Per cent. No. 2 Rag, 100 j No.3.... Rag, 75; wood i)ulp by sulphite process, 25 Rag, 75; wood pulp by sulphite process, 25 All manila 25 26 No. 4.... No. 5.... ■■"i o Ma alia. ^Ground wood. The total quantity of paper ordered on this contract was nearly 3,000,000 pounds. As the price of chemical w^ood paper is from 3^ to 3^ cents a pound, while rag paper is worth from 15 to 20 cents a pound, and manila paper brings 5 cents a pound as compared with unbleached chemical wood paper at 2f to 3 cents a pound, the saving to the Gov- ernment in value of goods received by the institution of these tests is readily seen to be enormous. The tests reported in Table II represent an extended study of the better class of writing papers as to their quality, strength, and relative value for permanent records, and are illustrative of the examinations made to determine suitability for a specific use. The kind of stock, strength, sizing, and ash show the general quality and nature of the paper, and on these determinations, together with the loss of strength on folding, the reaction, and the quantity of salts present in the paper, an opinion as to the relative durability of the papers submitted may be formed. Table II. — Examinations of writing papers, with special view to their durability for permanent records. Determinations. Serial numbers. 1128. 1129. 1130. 1131. 1132. 1204. 1205. 1206. 1207. Stock: Rag per cent. . Wood pulp (sulphite process), 100 100 40 25 35 123 0.116 7.9 4,564 66 3.1 90.3 0.69 n («) (0 100 100 100 100 89 11 71 29 Wood pulp (soda process), per cent . ... Weight (per sq. m.) grams. . Thickness millimeters. . Breaking weight kilograms. . Breaking length meters. . Loss of strength on folding . .per cent . . Stretch do Loss in stretch on folding do ... . Ash do.... Sizing 90 0.108 8.0 6,344 9 6.5 15.0 0.73 n 113 0.125 9.3 5,843 10 4.7 35.5 0.72 i-i (0 104 0.113 9.4 6,466 24 5.5 15.1 0.60 («") {^ (0 90 0.104 7.6 5,942 19 5.2 33.2 0.81 108 0.120 10.5 6,792 22 5.6 47.9 0.56 (») Trace. (0 110 0.129 10.3 6,651 21 4.9 43.5 0.67 Trace. (0 116 0.125 9.5 5,764 33 4.1 65.7 0.94 (^) 105 0.116 6.1 4,998 38 2.6 68.5 3.75 (b) ('') i C**) Chlorlds Trace. Trace Sulphates . («) («) o Animal and rosin, b Animal, rosin, and c Neutral. starch. a Faintl Mediu y acid, m. rear. 84} In examining the results on these nine papers it will be seen that all except Nos. 1130, 1206, and 1207 are satisfactory as to the kind of stock which they contain. In breaking length the same three papers are lower than the others and show a greater loss of strength under the folding test. Papers Nos. 1130 and 1207 are below the standard in stretch, which for this class of papers should be at least 4 per cent. The three papers first mentioned also show the greatest decrease in stretch in the folding test. In ash all of the samples are satisfactorily low except No. 1207. The sizing of all is good, although it would be better to omit the starch from Nos. 1131 to 1207, inclu- sive. In reaction Nos. 1128, 1130 and 1131 are neutral, while all of the others are faintly acid, which is undesirable. All of the samples contain more sulphates than should be found in the best ledger paper, and the same is true of chlorids for Nos. 1128 to 1132, inclu- sive. Considering all the evidence, papers Nos. 1130, 1206, and 1207 would be rejected on stock, strength, and folding; Nos. 1130 and 1207 also on stretch, and No. 1207 on ash as well. The other papers are all good, with the advantage in favor of No. 1128 on account of its neutral reaction and small loss of strength and stretch on folding. CHARACTERISTICS OF PAPERS FOR VARIOUS PURPOSES. The selection of suitable papers for specific purposes is not always an easy matter, and the following broad statements as to the char- acteristics that different papers should have may be of service to purchasers in preparing specifications; more detailed specifications could be suggested for any particular case. The value of a paper may be considered from two points of view — that of quality and that of utility. In the former case the question of cost is considered but little, the object being to secure an article of the finest kind and most pleasing appearance. Such papers are used for special purposes, for example, fancy writings, editions de luxe, etc., and constitute but a small part of the papers made. Con- sidering the utility of a paper, it should have the special characteris- tics which make it suitable for a specific purpose, the finish, texture, and stock being no better than the work to be performed demands. RECORD PAPERS. The papers used for recording deeds, for court records, vouchers, receipts, ledgers, and all Federal, State, and county records which are preserved for many years and subject to much handling, should be strong and uniform, and to this end should be of the best rags and manufactured by the best processes, being well washed to remove bleaching agents and soluble salts. Such a paper should not be over bleached; should be well but not over sized, using animal sizing and [Cir.34] 8 a minimum quantity of rosin to insure good erasures; it should be neutral, or nearly so; should not be loaded; should be loft or pole dried rather than machine dried, and should have a smooth, even surface. BOOK PAPERS. For publications of permanent value book papers should be of the same general character as record papers. The sizing should be of rosin alone. When loading is used it should not exceed 10 per cent. * For less valuable books papers of lower grade containing, in addition to rag stock, chemical wood pulp, esparto, etc., maybe used and less care exercised in their making. For books and papers of transitory value rag stock need not be used, second-class stock, such as chem- ical wood pulp, esparto, etc., serving every purpose. Overloaded papers should not be used for any class of work, as they are needlessly heavy and much weaker than the same paper unloaded. Loading makes a paper more opaque and better suited to the use of certain inks ; it also serves as a substitute for beating, in that it hides imper- fections in a poorly made sheet. For books containing a large number of pages a thin paper, provided it is sufficiently opaque, should be used, in order to secure a volume of good proportions. For coated papers the same general specifications hold, except that more loading is permissible. WRITING PAPERS. The best grades of writing papers used in correspondence which partakes of the nature of permanent records should be strong, uni- form, well-made rag papers not loaded and quite similar to record papers. A cheaper paper may be used for less permanent corre- spondence, being of poorer quality as to stock, texture, etc. ENVELOPE PAPERS. As envelopes are but short lived they need not be of the strong rag papers described above. It is sufficient that the envelope have a good writing surface, be opaque, and strong enough to carry its contents safely to their destination and appear well when delivered. Any stock and character of paper of the desired color which will fulfill these requirements will serve the purpose. For instance, a well-made paper containing 50 per cent of rag and 50 per cent of sul- phite stock is satisfactory for the ordinary correspondence envelope. Very strong papers are of course necessary for international use or the transmission of large and heavy documents. Envelope papers should not be loaded, should be well sized, and have an even, firm surface. [Cir,34] 9 BLOTTING PAPERS. The value of blotting papers is determined by their absorptive power. They should be rather loosely made and the best grades should not be loaded. WRAPPING AND BAG PAPER. The important qualities for wrapping and bag paper are strength and pliability, which should not be sacrificed for other character- istics. Jute and manila are recognized as giving a paper of this kind, but any stock which will insure the properties named may be used. A paper known as ''Kraft brown," made by a special method of treating wood, is now coming into prominence for these purposes. It apparently is much stronger than the ordinary papers heretofore made from chemical or mechanical wood pulps and promises to serve as a substitute for jute and manila papers in certain cases. Papers used for wrapping polished metals should be free from acids. The more perfectly wrapping papers resist water the better, provided that strength is not sacrificed in securing this quality. DIRECTIONS FOR SECURING AND FORWARDING SAMPLES. If possible, each sample for examination should consist of ten sheets 12 by 12 inches, and each sheet should be taken from a dif- ferent part of the lot of paper. The sheets nmst be shipped flat and so packed as not to be broken or creased in transit. Samples positively must not be folded or rolled. — If it is impos- sible to secure ten sheets of the desired size, smaller samples may be taken, but the examination made may be limited by the quan- tity and condition of the sample. Each sample must be fully identified by numbers or other marks and labeled with the name of the sender; name of manufacturer, when obtainable; the class to which it belongs, as ''ledger," ''book," "writing," "blotting," etc.; the purpose for which it will be used; the manufacturer's or dealer's claims as to quality, as "all rag," "half sulphite and half soda," etc.; weight and size per ream, and cost per pound. The sender should not fail to indicate the nature of the examina- tion desired — that is, whether compliance with specifications is to be determined or suitability for a given purpose. If the former exam- ination is desired, a copy of the specifications should be furnished, and if the latter, the purpose for which the paper is to be used should be stated. [Cir.34] 10 Samples should be forwarded by mail or prepaid express, addressed as follows, and the Bureau notified b}^ letter of the shipment of the samples : Bureau of Chemistry, Z7. S. Department of Agriculture, Washington, D. C. Leather and Paper Laboratory. Attention is called to the fact that examinations can not be made for individuals, manufacturers, or dealers. F. P. Veitch, Chief, Leather and Paper Laboratory. lCir.34] o RETURN MAIN CIRCULATION ALL BOOKS ARE SUBJECT TO RECALL ■ RENEW BOOKS BY CALLING 642-3405 DUE AS STAMPED BELOW FEB 01 U 96 RECEIVED NOV 0 2 1995 CIRCUUTION DEF ■ FORM NO. DD6 UNIVERSITY OF CALIFORNIA, BERKELEY BERKELEY, CA 94720 UNI^ 14 DAY USE RETURN TO DESK FROM WHICH BORROWED LOAN DEPT. This book is due on the last date stamped below, or ^^onXe date to which renewed. Renewed°b,Sks a« subiect to immedute recaU. ■II i4tD00 XX AUG 2 9 1975 9 ?;, 4ftA^^^*^98^ mc CIR. APR 8 1981 TJEU"M983 LD 2lA-60m-10,'65 (F77638l0)476B General Uhtary University of California Berkeley YC 69407