43rd Annual Meeting – Research and Technical Studies, May 15, “Parylene Treatment for Book/Paper Strengthening” by John Baty

In the 1990s there was a pioneering study on the use of parylene to strengthen brittle book paper performed by Don Etherington, David Grattan, and Bruce Humphrey. Ultimately their research did demonstrate that parylene strengthened weak, brittle paper, but several concerns regarding the material’s long term effects were raised; such as reversibility and the uncertainty of its aging properties. John Baty and his colleagues at the Heritage Science for Conservation Research Center at Johns Hopkins University, sought to reexamine the potential for using parylene to strengthen brittle paper, given the improved scientific instruments and analysis methods available today. Their research sought to answer five primary research questions:  does parylene strengthen paper, what is the permanence of its effect, what are the side effects, how can parylene treatment be scaled up, and how can it be reversed.  Currently they have answered the first two and are conducting ongoing research.
Parylene is applied to brittle books by using a chamber that draws a vacuum and essentially pulls sublimated parylene through the system. The amount of parylene dimer that is added to the chamber directly correlates to the thickness of the deposited film. Previous research had not optimized the amount of parylene needed to achieve a desirable film layer, so this was a primary goal for Baty and his colleagues. The success of the treatment was evaluated using three mechanical paper strength tests: tensile testing, the MIT fold endurance test, and the Elmendorf tear test.
Baty and his team found that using 3 grams of parylene was sufficient to strengthen brittle paper to the point that it behaved similarly to modern wood pulp paper and only imparted a smoother appearance to its surface. 5 grams of the dimer was too much and conservators inspecting the pages concluded that the paper had a more “plasticky” and stiff feel to it. The three mechanical tests did indicate that the brittle paper samples were strengthened with the addition of a parylene coating, but there are still questions regarding this treatment’s reversibility and side effects that remain to be answered by Baty and his team in subsequent research.

One thought on “43rd Annual Meeting – Research and Technical Studies, May 15, “Parylene Treatment for Book/Paper Strengthening” by John Baty”

  1. This is a very interesting revisit of the 1990s investigation into parylene treatments. My question for the researchers are why would parylene be the desired treatment plan for brittle paper? If we are going to plasticize brittle papers, clearly we have determined that the material nature of the object is not the primary goal. In that case, why wouldn’t we just digitize the object or even photocopy it if we are talking about newsprint or some other purely informational item?

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