Repairing the book structure
The book itself has a large textblock of machine made wove paper, sewn and glued together in 1855. The original animal glue on the spine and holding the silk endpapers in place was now becoming brittle, and the block of pages consequently becoming loose. The fragile silk joints used in 1855 to attach the heavy decorated boards to the book were taking much more strain than they should, because the glue was failing. So the book itself had to be repaired and made strong enough to support the heavy binding.
The silk endpaper hinges were lifted from the joints, the attachments were repaired or replaced, and the lower attachment was reinforced with Japanese paper strips, using wheat starch paste as the glue. The existing lining of the spine of the book was not strong enough to serve as a base for the new board attachment and the animal glue originally used in 1855 was acidic and had now broken down, so a new spine lining had to be built. This was done using aerolinen and acid free paper. These are inert compounds which will not degrade over long periods of time. They are used extensively in conservation so that the repairs done now will last for several centuries.