NEH Effects of Relative Humidity Fluctuations on Paper Permanence

The goal of this research is to use analytical data to define a relative humidity (RH) range and fluctuation rate that does not cause permanent physical and chemical damage to paper-based objects. This project follows up on an initial study completed in 2001 that examined the degradation of cotton paper when exposed to humidities cycled between 25% ? 75% every two hours at room temperature. The next step in that investigation will be exploring in more depth the key factors that may determine the magnitude of risk, paper composition and humidity excursions. The principal activities will be to generate data by exposing three types of paper?a rag paper control, an acidic newsprint, and a modern alkaline book paper?to fluctuating humidity conditions. Those humidity environments will explore different ranges of excursions?a small one in line with the current definition of ?safe,? and a larger one more similar to an environment with little or no humidity control. Tests will also examine the effect of the rate of humidity shift: a rapid one, in which large shear forces may result from wet-dry interfaces within the paper, and a slower shift, which would allow more gradual equilibration that might mitigate the internal shear forces. The molecular weight of the cellulose, as well as the tensile strength and elasticity, color, and moisture content of the tested papers will be measured in order to characterize the stability of paper-based artifacts in these environments. The expected result will be quantifiable evidence of the risk of exposing paper-based artifacts to large and rapid changes in relative humidity.<br>There are three major reasons why this work will have a significant impact for archives, libraries, and museums. One, it will clarify more precisely the environmental conditions that are necessary to best preserve paper-based artifacts; as recently as 2014, discussion and debate regarding truly safe storage and display conditions for hygroscopic materials was still ongoing. Two, the conditions delineated will be defined by scientific data acquired in laboratory experiments that simulate the storage environments (and are not inferences derived from testing performed at elevated temperatures, for example). Three, the findings of the research will greatly aid sustainability planning, informing the level of climate control that is necessary for collection preservation.<br><br> Works of art on paper: books, documents, and photographs: techniques and conservation; contributions to the Baltimoar Congress, 2-6 September, 2002<br><br>