Rigid Gels for Paper Conservation

A workshop participant in the process of making thin cast rigid gel

Jamye recently attended a workshop at the Kislak Center for Special Collections, Rare Books and Manuscripts at the University of Pennsylvania to learn more about working with rigid gels. This was the first time such a course was offered for paper conservators, and Jamye received a professional development grant from the Foundation for Advancement in Conservation (FAIC) to support her attendance. While gels have long been used by paintings conservators, they are a relatively new addition to the paper conservator’s toolkit.

A rigid gel is made by mixing a small amount of agarose or gellan gum–an edible, non-toxic product used in food manufacturing–into purified water. Calcium acetate is added in minute quantities to gellan to stabilize the solution. When the components are mixed and heated, the conservator must work quickly to pour/flatten the gel, by pressing it down with a piece of glass or plexiglass for thin cast gels (seen in the image above) or allowing it harden in a tray for thick cast gels (below). Once the gel sets, it is very stable and will last a few weeks in refrigeration.

A sheet of thick cast rigid gel with an object for “washing”

Rigid gels are a controlled method of applying moisture locally or overall to an object for the purposes of “washing” or removing attachments. The conservator can adjust the amount of moisture introduced by altering the proportions of gellan gum to water. The gel can be cut to the exact shape of a discolored area, for example, and its capillary action will work to pull out the discoloration. In the images below, you can see an example of Jamye using a gel to remove the oddly shaped black paper that was adhesed to the back of an object with gel cut to match. While some mechanical (i.e. manual) action is still required to fully remove the black paper remnants and the adhesive, it is dramatically reduced and so causes less wear on the fibers of the object being treated.

The non-toxic gel is safe for both conservators and the environment and furthers the goal of finding more planet- and people-friendly methods of treatment in our field. More testing is needed to understand all of its applications, but it appears to be an extremely promising method of treatment for paper conservators moving forward.