AIC's 52nd Annual Meeting

Often, the way to deal with complexity is to create categories that allow us to make sense of the world. However, challenge arises when those structures become rigid and siloed, allowing previously assumed knowledge to become the accepted theory. Over the four years of the Mellon-funded “Assessing the Condition of the National Collection” project, the preservation staff at the Library of Congress compared 500 of the same paper-based volumes of the same title from five different research libraries in distinct environmental regions of the United States through photo-documentation, visual assessment, and physical, chemical, and optical test methods. These roughly 2500 volumes were published throughout a 100-year period from 1840 to 1940, when Western paper production experienced wide-ranging changes, such as shifts from rag to wood pulp, sizing chemistry, and the use of new paper-making equipment. During testing, we were confronted daily with observations and technical data that did not align with our accepted assumptions of book paper materiality. We quickly found that sets of the “same” book frequently showed more differences than similarities in their materiality. We were expecting these “same” titles to largely be identical to each other. However, roughly 25% of the time, different copies of the same title showed evidence of significant differences in materiality, spanning printers’ marks, predicted pulp composition, and physico-chemical properties. Our new “assumptions” were instead that the sets of books from this time period were surprisingly likely to be different in composition. These variations in composition were also found within the same volume, where at least 15% of books tested had multiple paper types. While mixed paper types within one volume are not completely unknown, the extent of their occurrence surprised us, making it difficult to generalize about specific measurements from a single volume when we could clearly see material differences within that book. Some variations led to deeper explorations of why these trends occurred and what the practical preservation consequences might be. Some explanations may implicate societal changes that resulted in considerable experimentation in paper production, such as WWI, the economic downturn, increased mechanization, and different interest levels in specific literary categories. We found that the different geographic regions holding these books had no connection to their current condition. The technical testing data was complex and multivariate, offering no immediate clarity. To deal with this complexity, chemometrics and statistical modeling methods were employed to allow for the identification of subtle trends and more careful or alternative groupings in the data, such as the extent to which colorimetric properties can or cannot correlation to the physical condition. This work will discuss the various upending of our assumptions and broader learnings from this project as we continue to explore its data.