Emily Hishta Cohen presented a technique for repairing case bindings, where the case has detached from the textblock along one or both board joints. This technique was developed in the MIT Libraries Preservation Department, and continues to be used there frequently in the repair of books belonging to both special and (more recently) circulating collections.
The technique is essentially a modification of a hollow tube repair, except that the tube is gradually constructed on the book using layers of tengucho (or other very thin Japanese paper), adhered with a mixture of wheat starch paste and methylcellulose. Silicone-coated Mylar is used to prevent the tube from adhering to itself as the repair dries. After the spine hollow is reconstructed, internal hinges of tengucho are adhered along the inner board joint(s) to reinforce the repair. Notably, this technique preserves all existing spine linings. Rather than cleaning them off, as with traditional re-backing techniques, here they are left in place and re-adhered as necessary. The best way to understand how this repair is executed is to watch a very thorough step-by-step video created by the MIT Preservation Department, available at this link: http://bit.ly/MITRBBS.
This technique is reversible, minimally interventive, and preserves all existing components of a binding, all of which are admirable qualities in a conservation treatment. It appears perfectly suited to cloth covered case bindings of a relatively small size (such as the one that appears in the video). The abstract mentions that the technique can be modified for larger, heavier books by using cloth in place of Japanese paper. I would be interested in seeing how this would be done without removing existing spine linings to make room for the extra bulk of the repair cloth, which would be significantly thicker than tengucho.
Regardless of how it might be adapted to more substantial books, this “re-engineering” technique is a reminder that sometimes, the weaker repair material is the ideal choice. I’ll certainly keep this technique in mind. A conservator can never have too many tricks up her sleeve.