This is another book from the Syracuse University Ranke Collection that was a good candidate for rebacking. The sewing was completely intact (on raised cords), but the leather at the spine and joint was delaminated.
I was able to remove most the leather from the spine dry, and applied a thin layer of methyl cellulose to remove the rest. Then, I pasted out the spine, and lined it with Japanese tissue. While that dried, I cut strips of linen to be glued down between the cords. Then, I resewed the end bands.
Using a scalpel, I cut along where the leather meets the paper on the boards. I removed the old leather, and lifted the paper slightly. I also lifted the endpapers at the corners and at the spine, for the turn ins. (I also put some brown Morike underneath the lifted paper for support. The paper was brittle and kept breaking. Adding the Morike enabled me to handle it without causing more damage). I measured and cut the new leather and prepared it by paring, dampening with a sponge, pasting it out, and allowing it to sit for the paste to soak in. Then I reattached the boards by gluing out the linen strips and bringing them on to the board. I trimmed the linen so it only overlapped by about half an inch. Then I cut two strips of 10 point board, the exact distance from the spine edge of the board to about 1mm before the paper. This makes the transition between the new and old materials smoother. After gluing down the 10 point strips, I attached the new leather to the corners, and put some silicon release paper between the board and text block. Then I attached the new spine leather, running a bone folder along the cords to accentuate them, and leaving enough material at the turn in to construct the head/tail caps. I wrapped a piece of cord around the joint, and put the book in a press to dry.