Paper as a carrier for written information was introduced in Europe in the twelfth century and slowly gained acceptance over vellum and parchment because of its availability and lower cost. Paper was made from recycled vegetable fibers from native European plant sources such as linen, and later from the nonnative fibers, such as cotton, originally made into cloth. Rags were pounded into a pulp that was mixed with water to form a suspension into which a frame with a covering of wire mesh was dipped (Hunter 1978, 153-154). The water drained through the frame leaving the pulp that was then pressed onto flat wool fabric to continue draining. The pulp removed from the wool fabric was pressed and dried to produce a sheet of paper. The surface of this paper sheet was usually coated with an animal-derived gelatin to size it. Sizing created a surface on the paper resistant to liquid adsorption that prevented ink from sinking-in and feathering (Hunter 1978, 170-194).
As the demand for paper increased, the quality of the fiber used declined at the same time that the manual methods of production gradually gave way to mechanization. There is a long recorded history of complaint about the quality of paper, first as a poor substitute for animal skins, and later as each type of vegetable fiber replaced the earlier one. Mechanization of the manufacturing process resulted in loss of fiber strength through cutting and grinding of rags rather than pounding them to produce the pulp. Compounds such as calcium hypochlorite and chlorine bleach were added to the pulp to compensate for the yellowed and rotten rags that were increasingly being used. Bleaching further degraded the fibers. Adding acid to the pulp in the form of alum lowered its alkalinity, that is, the added alum moved the pH of the pulp down towards the acid level. a different acidic substance than the previously-mentioned alum, aluminum sulfate or papermaker's alum, was later introduced to size the paper. By the 1800s this trend toward increasing acidity resulted in paper that was acidic from surface to interior. Thus, the durability and permanence of modern paper was inferior to paper made hundreds of years earlier (Shahani and Wilson 1987, 240-241).
Barrow was only one in a long history of individuals concerned about the permanence of modern paper. Concern over permanence was expressed as early as 1823 (Grove 1966, 21-22) by John Murray. Murray, author of several tracts on chemistry and paper deterioration (Murray 1924, Murray 1929), wrote some of the most frequently quoted descriptive language about rapid paper deterioration in a letter to Gentlemen's Magazine: "Allow me to call the attention of your readers to the present state of that wretched compound called Paper....Specimens there are, that being folded up, crack at the edges, and fall asunder; others, that being heated at the fire, disintegrate and tumble to pieces" (Murray 1823, 195). in a longer work published the next year he continued his description: "[A Bible, for example] CRUMBLING LITERALLY INTO DUST, and which was in this state, in parts, before ever the volume was used....Some of the most expensive works of modern times contain within themselves the seeds of destruction and the elements of decay....I have watched for some years the progress of the evil, and have no hesitation in saying, that if the same ratio of progression is maintained, a century more will not witness the volumes printed within the last twenty years (Murray 1824, 197).
Murray used contemporary chemical tests to analyze and identify these "seeds of destruction." He found the major causes of paper deterioration by examining the compounds remaining in badly deteriorated paper. He blamed the presence in the paper of excessive amounts of acids caused by over-bleaching and by the addition of excessive amounts of alum and alum rosin sizing for this deterioration: "The large portion of allum water mixed along with the pulp is a most reprehensible and destructive practice, and is what my chemical investigation discovered: not only is the texture disintegrated thereby, but the excess of sulphuric acid in the supersulphate must discharge the ink. Here indeed might be matter for legislative interference. No acid, whatever, either free, or in the form of a supersalt (such as persulphate of alumina, binoxalate of potassa, &c.,) should be permitted" (Murray 1824, 199). Paper chemists worked for the next 100 years to establish in detail and with confidence the dynamics of acid deterioration based upon the culprits Murray identified in 1824.
Although no legislation against the use of acids in paper making was passed, papermakers soon learned to control the ill effects of bleach. The continued use of alum though resulted in high acidity. Alum use even increased in the early 1800s when Moritz Illig, son of a German papermaker, invented a process to introduce a size made from alum and rosin into the pulp before sheet formation (Renker 1961, 37).
By the late 1800s inexpensive wood fiber had replaced cotton as the primary vegetable source of paper. Either of two chemical processes — sulfite or soda — was used to separate on a mass scale cellulose fiber from the non-cellulose materials that make up the remaining 50% of wood. The groundwood process, a German invention in 1840, provided an even less expensive way to make paper pulp from wood, and by the 1860s groundwood was in general use worldwide. Logs were ground up and used without chemical processing to remove the non-cellulose components of the wood, such as lignin, which up to this time had been regarded as impurities in paper manufacture. Groundwood pulp contains cellulose fibers shortened by grinding and lignin that deteriorates rapidly. Paper made from groundwood is both weak and impermanent (Shahani and Wilson 1987, 241).
The paper used in the western world for writing and printing from the mid-1800s suffers from impermanence because of changes in fiber, changes in manufacturing techniques, the addition of acidic compounds, and their residues in the finished product (Shahani and Wilson 1987, 241-242).
Chemistry as a modern science had its beginnings in the early 1700s. in the next hundred years various branches and specialties developed to study phenomena with economic application. Paper chemistry was one of the areas where application had great economic importance. It was, therefore, one of the first areas where applied research was done. Murray's work and publications were near the beginning of the history of paper chemistry. Even at that time, chemists knew a great deal about the dynamics and mechanisms involved in paper deterioration. The details of the chemical dynamics involved in paper deterioration were learned through a process of experimentation over the century that separated Murray and Barrow. Even a preliminary search of the literature on paper chemistry reveals that the chemical findings Barrow had been credited with discovering existed in the literature of paper chemistry long before he began to restore documents in 1931. Studies in paper chemistry and patent literature relating paper characteristics of permanence and durability have been abundant, especially since the late Victorian era (Smith 1969, 154).
Because of the complex and varied nature of the composite material referred to as "paper", research findings in paper chemistry are difficult to accurately interpret for the professional chemist, and more so for an amateur, even for a dedicated one like Barrow. Paper is a compound substance. As such it requires measurement by both chemical and physical means in order to understand its characteristics. Dwan, a paper conservator, has stressed the complexity of research in paper chemistry and the importance of proper interpretation in the usefulness of its findings and application in conservation.
The composite nature of paper limits the usefulness of testing isolated components, either chemical or physical. It is difficult to relate a single component back to the overall structure. The usefulness of chemical testing may be limited by lack of correlation to the overall physical structure of paper. Likewise, physical tests cannot provide information on a chemical reaction, or predict permanence....the results of a particular test, chemical or physical, may be interpreted in a number of ways, and making the proper interpretations and conclusions depends upon the total research design and expertise of the researcher (Dwan 1987, 1).
Due in part to the alarm sounded by people such as Murray, active research in permanence and durability of paper had been carried out in Europe and the United States, especially since the late 1800s. Chemical Abstracts, from its inception in 1907, has carried citations to articles explaining the chemical nature of paper and its effects on all of its characteristics, measured both chemically and physically.
attention . . . [was called] twenty years ago to the uncertain future of the paper in modern use for many books and periodicals. at that time it was found that out of 100 periodicals of permanent value, only 6 were printed on paper which was likely to last for many years....One instance is given of a work, published in 1881, which is now falling to pieces. The properties of the paper . . . [included] elongation 1.8%, folding-class 0 (one double-fold), resistance to crumpling extremely low. The fiber composition was, linen 40, cotton 30, wood-pulp 25, straw-pulp 5. The ash was 21%. This example shows clearly that the fiber-composition is not the only important consideration, for this paper was 70% rag, and contained no lignified fiber. The physical tests are just as important as the composition, because the best of fiber can be so handled as to make the poorest of paper. in the present case, an additional outlay of . . . [a few] cents, . . . a volume, . . . would have permitted the use of paper . . . [that] would probably last for centuries (Herzberg 1907, 2634).
A bibliography by Robert Walton of the New York Public Library was published and widely publicized to the library community in 1929; it contained 100 citations to articles on paper permanence.
Paper chemists from the Government Printing Office, Morris S. Kantrowitz, Ernest W. Spencer, and Robert H. Simmons, identified 290 articles dated from 1885 to 1939 in chemical literature and library literature on paper permanence (Kantrowitz, Spencer, and Simmons 1940). Jerry Byrne and Jack Weiner from the Institute of Paper Chemistry identified 19 additional articles dealing with acidity and its effects on permanence that had been published in the literature of paper chemistry from 1910 to 1940 (Byrne and Weiner 1964). The chemical literature progresses from a focus on the inferiority of groundwood pulp, sulfite cooking processes, and environmental causes of deterioration to studies of the role of lignin and residual acids from a variety of sources in the process of paper deterioration (see Appendix 4).
Permanence studies in the paper chemical literature were common knowledge to chemists in the field. Barrow had personal friendships and actively corresponded with some of the most knowledgeable paper chemists in the nation from the NBS and the GPO during the most active period of research on paper permanence at these institutions. These chemists not only knew the work of others but also contributed outstanding research in paper chemistry themselves. Barrow received a copy of the Kantrowitz bibliography directly from Morris Kantrowitz as soon as it was published in 1940 (Kantrowitz 1940). Chapter 9 details Barrow's interaction with these Washington experts.
Of the earliest reported articles in Kantrowitz, from 1885 to 1904, 20 concerned the deterioration of modern paper. of these 20 studies, 50% dealt with fiber content as the major cause of deterioration. the rest of the articles dealt with external causes, such as heat, and internal causes, such as acidic chemicals residual from modern manufacturing techniques, and added acidic chemicals from the use of alum rosin size. Non-chemists wrote most of the articles that identified wood fiber and environmental pollution such as coal gas as the major causes of rapid paper deterioration. This early research is limited because standards for measurement of paper's physical characteristics did not yet exist. Much early research was devoted to studying ways of testing paper characteristics and developing effective methods of accelerating aging of paper to study the effects and dynamics of aging in paper through a type of simulation of the effects of the passage of time (Kantrowitz, Spencer, and Simmons 1940, 99-108).
When groundwood pulp was invented and used in Germany, the problems of rapid paper deterioration it caused, combined with the advanced level of chemical research in Germany to produce the first modern and systematic studies in paper permanence beginning in the 1880s (Conroy 1984, 1). an example of the early German work is an 1888 study by Würster on the dynamics of acid-caused deterioration. He concluded, after 10 years of observation, that "sulphate of alumnia [sic]" has a strongly caustic action if chlorides are present. High temperatures exacerbate the deterioration. Chlorides in paper result from inadequate washing following bleaching (Würster 1888, 338).
Early studies were carried out on the relationship of fiber content to acid damage. for example, in 1903, Little determined that wood fiber paper could be long lasting. He postulated the cause of rapid deterioration to be the combination of weakened fibers and residual chemicals from the bleaching process, rather than the type of fiber alone (Little 1903). Researchers agreed that bleaching caused deterioration by weakening fibers and leaving residual chloride that reacts with cellulose. But by at least 1900 it was also generally known that sulfate, from alum-rosin size, within the paper sheet converted to sulfuric acid that also reacts with and deteriorates cellulose (Residual chemicals 1900, 24). As early as 1895, many other studies supported Würster's early work showing that acid hydrolysis, due to the sulfur released from the deterioration of rosin size, was recognized as just as responsible for paper deterioration as the oxidative process released by the chlorides residual from the bleaching process (Resin sizing and the durability of paper 1895, 1059). By 1903, Winkler had not only pinpointed the chief cause of rapid paper deterioration as acid hydrolysis from sulfuric acid, not from hydrochloric acid, but also had detailed its mechanism (Winkler 1903, 160).
These early studies support current understanding of the chemical dynamics of modern paper deterioration. But contemporary with these studies were other research and interpretations of data that supported older ideas of deterioration. for example, the Committee on the Deterioration of Paper of the Society of Arts published a report in 1898 finding that bleaching and air pollution from gas lamps are the most important causes deterioration. This study was most influential in the development of contemporary ideas about deterioration among librarians and archivists (Society of Arts 1898) perhaps because its conclusions were more accessible to non-chemists.
By the turn of this century, most large paper companies employed chemists to monitor and develop manufacturing processes, and to do product research. in addition, government agencies in Europe and in the United States did research on topics related to development of standards, measurements, tests, and quality control, some of which research was related to paper and its characteristics.
In the 1800s progress in the study of paper deterioration was slow because the properties studied required decades to show measurable changes. There were no means to speed the aging process so that the effects of age could be efficiently studied. Different chemists found different, even conflicting, results because paper samples, storage conditions, physical tests, and testing equipment varied, not only over time, but also, among companies, laboratories and countries. As procedures and methods became standardized, consistent results began to appear by the 1910s (Conroy 1984, 1).
From the early 1900s to the mid 1920s Kantrowitz records 77 articles (see Appendix 4): of these, 56 dealt with causes of deterioration and 21 dealt with other topics, tests, protections, new techniques, and interpretations of prior research. in summary, 38 articles identified acids as the cause of paper deterioration. This represents 68% of the articles dealing with causes of deterioration. All the articles that identified wood fiber as the cause were by non-chemists. These studies made up only 4% of the articles dealing with causes of rapid paper deterioration (Kantrowitz, Spencer, and Simmons 1940, 66-99).
As early as 1907, Winkler showed acids to be harmful to paper, even in the smallest amounts. Winkler urged paper manufacturers not use acids at all (Winkler 1907, 271). By 1911, all current ideas about deterioration of paper as a combination of internal chemical processes and external environmental factors were detailed by Wrede in a study that also emphasized sulfuric acid as the most injurious to paper of the various air pollutants (Wrede 1911). By 1920, research in paper chemistry had a distinctively modern sound, as shown by a summary of an article by Aribert and Bouvier.
The durability [and permanence] of paper depends on (1) the nature of the stock used, (2) the treatment to which it is subjected during its transformation into paper, (3) traces of chemicals remaining in the finished paper, (4) conditions under which it is kept. (1) Paper manufactured from cotton rag stock (normal cellulose) may last for centuries. Chemical pulp is much less resistant to the action of oxidizing and hydrolyzing agents, but when properly prepared it may . . . yield a very durable [permanent] paper. Mechanical pulp (impure lignocellulose) yellows very easily, becomes brittle and possesses very little strength. (2) the cooking of the raw materials should be just sufficient to dissolve out the impurities and incrusting matter; for both insufficient and excessive cooking yield a pulp requiring a very energetic bleaching treatment, which is very detrimental to its durability. The cooking must be followed by very thorough washing to eliminate all the soluble products formed during cooking. Proper bleaching consists in oxidizing all substances other than cellulose, without attacking the latter. The addition of acid, usually sulfuric acid, and the beating of the stock to hasten bleaching frequently result in impairing the quality of the stock....Properly purified loading materials are not detrimental to the quality of paper, if they are not added in excessive amounts. for rosin sizing....It is also important to avoid acidity in the alum....(3) the most frequent and most harmful chemicals remaining in the paper are free acids and free chlorine (Cl). These can be safely removed only by thorough washing....(4) the durability of finished paper is affected by light, temperature, and humidity, and the surrounding atmosphere. the yellowing of mechanical wood pulp is due to the oxidation of fats, waxes, resins, lignin, etc. brought about by light of short wave-length. Yellowing of paper made entirely of chemical pulp may be due either to an excessive cooking treatment to which the pulp was subjected or to traces of free acid or free chlorine (Cl), rosin, iron resinates, etc., the destructive action of which is much more harmful than the mere yellowing. Light may have a catalytic effect in breaking down cellulose or some of the impurities present in the paper. the paper should be kept at a proper and even temperature and under such conditions that it will retain sufficient but not too much moisture. Growth of fungi [should] . . . be prevented or hindered (Aribert and Bouvier 1920).
The early, mostly European, research in paper permanence was in some cases replicated, extended, and applied in the United States. The next chapter will show how Barrow found his way to this research.
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