Paper Strengthening through Paper Splitting Project
Background: Once paper becomes brittle, very little can be done to strengthen it so that items can be safely handled. The accepted traditional method is to line a document with thin, stable, translucent archival grade paper such as Japanese tissue, using approved stable and reversible adhesive. These methods can be very time-consuming. A faster production method for paper strengthening has been developed. This method was tested by LOC. Between 2002 and 2005 The Preservation Directorate of the Library of Congress investigated the viability of a preservation program that addresses the condition of those objects that are “too brittle to serve.” The extremely fragile condition of these objects not only excludes them from being served but often from being reformatted. The Library contains significant quantities of objects in this fragile condition, which makes expensive single-item treatment cost-prohibitive. The goal of this three-year pilot program was, therefore, to find and evaluate a cost-effective treatment protocol that can handle these objects in bulk.
Project Description: In 2002, ZFB (the Zentrum für Bucherhaltung) in Leipzig, Germany was the only company that provided mechanical paper splitting services on a commercial basis. In the ZFB process, a brittle paper sheet is temporarily "sandwiched" between two support paper layers, adhered to each side. After drying, the support paper layers are pulled apart, which splits the original paper. A new "core" paper is then inserted between the original paper halves and the entire package of layers is reassembled. The support paper layers are then removed by dissolving the adhesive in an enzyme bath. Following this, the original paper, with its newly inserted core paper, is pressed and dried. Washing and deacidification of the original paper is an integral part of the process, so both the physical and chemical condition of the paper is improved. The Conservation Division and the Preservation Research and Testing Division jointly conducted the evaluation of a large number of samples that were treated by ZFB.
Outcomes/Findings:
- The project team compared multiple treatment procedures and optimized the final treatment protocol
- Treated samples were aged artificially in the Preservation Research and Testing
- Treated samples had improved brightness, pH and tensile strength as compared to untreated controls after accelerated aging for 28 days at 90°C and 50% RH
- Newspaper pages were well suited to the treatment, so long as quality assurance was maintained
- The majority of US published newspapers exceed the paper splitting machine’s width
Support: Library of Congress Library Services
Acknowledgements: Zentrum für Bucherhaltung, Leipzig
Update and Images:
- March 2007: Results of the pilot program were presented at various conferences including American Institute for Conservation (AIC) and the Mid-Atlantic Regional Archives Conference (MARAC)
- October 2005: The program was completed in September 2005. A total of 35,000 sheets have been treated to date