To repair the exterior of the book, the leather must be lifted off the board with a lifting knife. Often, after over 250 years, the leather is in bad shape: thin, brittle and damaged. This leather was all of these things, and was easy to lift. In addition, the leather appeared to have been exposed to heat or some caustic liquid because it was very discolored and damaged along the spine area. After the leather was lifted, I inserted a light brown Japanese paper (Moriki) to bridge the break along the hinge between the spine and the boards.
The final step in the repair process is toning the exterior paper to match the existing color of the spine and cover boards. To do this, I used acrylic paints. When the paint has dried and you are satisfied with the color match, a mixture of methycellulose and alcohol known as Klucel-G is applied to the entire exterior of the book. Klucel-G is a leather consolidant and does just that: it consolidates all the dry and powdered leather particles into a hard surface. This makes your repair look seamless and hopefully almost invisible.