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research profiles Don’t touch that paper Imagine that you are the curator of an lectivity. Because real paper is often too for example, is a highly unstable natural amazing collection of historic docucomplex to allow for an exact analytical polymer whose effect on paper stability ments, irreplaceable works of art and lit- interpretation of spectra, the researchers is not clearly understood. Because of erature. You have two questions about a used PLS to correlate the spectral and lignin’s limited stability in light, howparticular map, which may be your most chemical information. With PLS, mulever, the amount of polymer present afvaluable holding—or a 19th-century tiple variables can be considered at the fects decisions about whether to display same time. a document. forgery. First, is this map authentic? If the answer is yes, the next question is The most important paper property A key feature of the technique is even more important: how do I preserve speed. Archivists and librarians frefor conservators is acidity. About 70– it? These questions can be answered quently must evaluate large collections 80% of Western library collections are fairly easily—all you need to do is rapidly degrading because of the cut a few square centimeters from low pH of paper produced since one edge for analysis. But that’s ~1850. The NIR analysis showed unthinkable, so the process stops. good correlation with actual Until now. destructive pH measurements. A nondestructive technique for Rapid analyses will allow libraranalysis of old documents, which ies to assess entire collections to provides details about the condidetermine whether books can be tion of the paper as well as its preserved or reproduced to save their content. age, was reported in the August 15 issue of Analytical Chemistry Although the primary concern (pp 6319–6323) by Tanja Trafela, of the project was characterization of the papers, the correlation Matija Strliˇc, Jana Kolar, and colleagues at the University of of the recorded data with the This map of the River Powhatan in New Netherlands documents’ known ages also was Ljubljana, the National and Uniwas made by Johannes Vingboons, probably after a map versity Library (both in Slovenia), striking. Clearly, the ability to acand Zentrum für Bucherhaltung made by David Pieterzoon de Vries, who made drawcurately date historical documents ings of plantations in Virginia while sailing on that river rapidly and nondestructively will GmbH (Germany). The group in 1633. (Copyright Nationaal Archief, The Hague, The be valuable to historians. used partial least-squares (PLS) analysis to relate near- and midNetherlands.) The team’s next step is the development of a portable instruFTIR reflectance data to paper properties, which were determined to establish the current preservation ment designed for the safe handling by classical analytical methods. These state and diagnose problems that should of objects. Curators, conservators, and properties—ash content, lignin content, be treated. The more valuable the docu- collection managers from large libraries, degree of polymerization of cellulose, ment, the more important it is to know archives, and museums will take part its current condition and the less likely and pH—are important for evaluating in this development. The SurveNIR the long-term stability of the paper. that its steward will make it available for instrument will be marketed through destructive testing. “This technique is Zentrum für Bucherhaltung. On the basis of changes in the chemical properties of paper as it ages, the likely to find use as a general quality“This will give the technique angroup also developed an application for control tool in conservation workshops other advantage,” says Strliˇc. “The a nondestructive dating of historical and in the development of new conserdocument does not have to come to the documents. lab—we can carry the lab to the docuvation methods,” says Strliˇc. “We also The research team compared its reforesee similar applications for synthetic ment. We will be able to perform rapid sults with those from destructive and materials and for textiles.” statistical surveys of large collections chemical tests on ~170 paper samples so that managers can plan for approConvincing PLS correlations were of known age, dating from 1650 to the obtained for several properties that indi- priate allocation of their conservation cate how the paper was made and how resources.” present. Although various analytical it has aged. These properties are imporThe person responsible for that methods use mid-IR and Raman techtant indicators that conservators use to priceless artifact will still be watching niques, the team chose the NIR range specifically because it is informationdetermine whether the document can nervously but breathing a bit easier. a rich, although it has low structural se—Steve Miller be safely displayed or circulated. Lignin, 6436
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