AIC's 41st Annual Meeting

Polyester film encapsulation has become a very popular method for supporting and protecting fragile or deteriorated papers. Even new paper, such as maps that are heavily used in libraries and archives are often encapsulated. Previous research on the role of encapsulation on paper aging is limited, but suggests that deacidification is necessary to slow the accelerated deterioration that encapsulated papers will otherwise undergo. Since it is very often not the case that papers are deacidified prior to encapsulation, this would suggest that many encapsulated papers in libraries, museums, and archives today are under threat of accelerated deterioration.
This study was conducted within the Heritage Science for Conservation project that is funded by The Andrew W. Mellon Foundation and located within the Sheridan Libraries and Museums—Department of Conservation and Preservation, Johns Hopkins University. Its purpose is to bring book and paper conservators, scientists, and engineers into the same working environment to research fundamental questions about materials degradation and conservation techniques; to expand the repertoire of scientific analyses to support conservation; and to develop information, products, and processes of demonstrated use at the conservator’s bench.
In this study, four different text-weight papers from the mid-1900’s, similar to those found in libraries and archives, were deacidified or left untreated, encapsulated, and aged at low temperatures (45°C or 60 °C) for up to 6 months. The aged samples were then analyzed for changes in pH and cellulose molecular weight using size-exclusion chromatography, as well as classical physical testing criteria. Aging conditions were selected to answer the most pressing questions regarding encapsulation, including (1) whether deacidification consistently makes a significant difference in the aging of encapsulated sheets, all else being equal—the “stewing in its own juices question”; (2) whether encapsulation makes a difference in the aging of acidic sheets—or of alkaline sheets—all else being equal; and (3) whether there is any significant difference in aqueous versus non-aqueous deacidification prior to encapsulation.