| AVS 61st International Symposium & Exhibition | |
| Conservation Studies of Heritage Materials Focus Topic | Thursday Sessions |
| Session CS-ThM |
| Session: | Conservation Studies of Heritage Materials |
| Presenter: | Lei Pei, Johns Hopkins University |
| Authors: | L. Pei, Johns Hopkins University M. Pollei, Johns Hopkins University S. Jordan-Mowery, Johns Hopkins University J. Baty, Johns Hopkins University |
| Correspondent: | Click to Email |
Parylene, the generic name for a class of polymers with the base monomer para-xylylene, has been used to strengthen papers via chemical vapor deposition. The deposited monomers polymerize in situ, forming a thin conformal coating that adds strength. Compared to other paper strengthening techniques, such as lining and paper splitting, which are mostly based on individual sheet treatment, parylene coating has the unique ability to treat all the pages of a book simultaneously. Parylene as a paper strengthening technique, however, has had limited recognition within the conservation community since the pioneering research was completed in the 1990s. The major conservation concerns centered at that time on how well Parylene coatings improve the durability of brittle papers and how well the treatment would enable future conservation intervention. One of the earliest criticisms revolved around reversibility of the treatment. No one would reasonably argue that it is desirable to return an embrittled book back to a state of embrittlement, which prevents its being used and/or its ability to accept other traditional repair techniques. Given that we cannot readily correct depolymerization of cellulose at this stage, the real value in parylene is the extent to which it will impart adequate material strength and be receptive to the range of traditional repair techniques as would be used on a non-embrittled book, and all other things being equal, how long the strength will last.
To answer these concerns and highlight the potential of this paper strengthening technique, we present the results obtained from mechanical testing and the behavior of parylene coated paper in standard paper conservation treatments. These results show that Parylene-treated groundwood pulp book papers from 1951 reveal many of the characteristics of a new wood pulp paper, in term of rattle, turn radius, and general tactile experience. The treated paper has over 30% improvement in tear resistance and more than three times higher folding endurance (based on a log scale of the number of double folds via an MIT folding endurance tester). Additionally, parylene treated paper is receptive to conventional paper conservation treatments such as traditional wheat starch paste and Japanese paper tear mending, guarding, washing and resizing. We will also discuss moisture content measurements to clarify concerns about the vacuum treatment involved in the Parylene coating process and its effect upon the treated paper.