<\/p>\n
Andrew began his talk by very graciously acknowledging that many other people have contributed data that informed his paper. Andrew\u2019s work is based on research began by William Barrow, a paper chemist at the Library of Congress until the 1960\u2019s. Barrow\u2019s research on books tried to draw a connection between physical properties and chemical content. He had collected about 1000 books published between 1500 and the 19th century, and he took various measurements such as fold endurance, pH, alum content, etc. He tried to draw connections between those sets of data to predict the ageing characteristics of the paper. This collection was obtained by LoC in the 1970s, and are still used for destructive testing today. But where Barrow used macro and micro scale measurements, Andrew looks to the middle ground: polymer chemistry. For that, he uses size exclusion chromatography, or SEC.<\/p>\n
SEC measures the degree of polymerization of cellulose using a roughly 1mm squared sample size. (It may be helpful to think of degree of polymerization as the molecular weight.) The degree of polymerization of a sample can be compared to known references. It should also be noted that papers have a mixture of molecules of different sizes, and SEC provides a distribution curve. The more large molecules in a sample, the less degraded the cellulose, meaning that the paper is in better condition. Andrew discussed several examples of treatments of iron gall ink on paper where SEC was used to show the effects of those treatments on the papers.<\/p>\n
Barrow\u2019s research indicated that pH was the best indication of the future physical properties of paper. Andrew took about 80 samples from Barrow\u2019s collection and confirmed that the molecular weights of paper correlate with pH (when the pH drops, the molecular weight drops). Andrew then looked to see if the molecular weight corresponded to physical properties; with newer papers, the molecular weight does tend to be smaller. Poor tear resistance also corresponds to low molecular weight. In general, he found that the molecular weight determined by SEC is a better indicator than pH for future physical properties for both newer and older books.<\/p>\n
SEC certainly has advantages. The sample size is ridiculously small. Tells you about the physical building blocks of the paper, giving a better idea of what\u2019s in it and what state the cellulose is in. There are some disadvantages to overcome before this technique is in every lab. The test itself takes a week to do. It requires extremely expensive equipment and organic solvents, and one must have the technical knowledge to interpret the data. Andrew\u2019s ultimate goal is to turn this into a rapid technique that\u2019s affordable, so that the molecular weight distributions of an object can be included in an object\u2019s record and be pulled up by a barcode. That\u2019s an exciting prospect!<\/p>\n
Andrew\u2019s work presents a very interesting analytical option that future conservators might have access to. It would be nice to have a predicting model for the degradation of library objects. But it would be even more interesting to see the effects of treatment on paper. It is important that conservators continue to check our own work, and I\u2019m glad to have assistance with that from scientists like Andrew.<\/p>\n","protected":false},"excerpt":{"rendered":"
Andrew began his talk by very graciously acknowledging that many other people have contributed data that informed his paper. Andrew\u2019s work is based on research began by William Barrow, a paper chemist at the Library of Congress until the 1960\u2019s. Barrow\u2019s research on books tried to draw a connection between physical properties and chemical … Continue reading “AIC\u2019s 45th Annual Meeting – Book & Paper + Research & Technical Studies group talks, May 31, 2017 – \u201cCenturies of Cellulose: Lessons Learned from the Molecular Size of Cellulose in Naturally-Aged Paper Collections\u201d by Dr. Andrew Davis”<\/span><\/a><\/p>\n","protected":false},"author":214,"featured_media":16731,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2,23,38],"tags":[79],"class_list":["post-17158","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-annual-meeting","category-book-and-paper","category-research-materials-techniques","tag-aics-45th-annual-meeting"],"_links":{"self":[{"href":"https:\/\/resources.culturalheritage.org\/conservators-converse\/wp-json\/wp\/v2\/posts\/17158","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/resources.culturalheritage.org\/conservators-converse\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/resources.culturalheritage.org\/conservators-converse\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/resources.culturalheritage.org\/conservators-converse\/wp-json\/wp\/v2\/users\/214"}],"replies":[{"embeddable":true,"href":"https:\/\/resources.culturalheritage.org\/conservators-converse\/wp-json\/wp\/v2\/comments?post=17158"}],"version-history":[{"count":0,"href":"https:\/\/resources.culturalheritage.org\/conservators-converse\/wp-json\/wp\/v2\/posts\/17158\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/resources.culturalheritage.org\/conservators-converse\/wp-json\/"}],"wp:attachment":[{"href":"https:\/\/resources.culturalheritage.org\/conservators-converse\/wp-json\/wp\/v2\/media?parent=17158"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/resources.culturalheritage.org\/conservators-converse\/wp-json\/wp\/v2\/categories?post=17158"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/resources.culturalheritage.org\/conservators-converse\/wp-json\/wp\/v2\/tags?post=17158"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}