Rebacking is a treatment typically performed when the text block has broken at the joint in the following three ways: where the endpapers fold, where the boards are connected to the text block (linen or mull spine liner in cloth bindings and the cords that lace on boards in leather bindings), and the cover material. Rebacking consists of constructing a new spine piece out of durable/flexible paper, and using it to reattach the text block and boards so the book can function properly.
To illustrate the process with full leather bindings, I selected four dictionaries from the collection at Syracuse which needed rebacking. All front covers were detached from the text block, and about half of the back covers. Spines had split away from the covers and had several bits missing and all the endbands cracked and coming away from the text block. The following images depict this condition.
I began by putting the spine piece in position. I work with the book flat on the bench so the spine piece is weighted down by the text block. I glued out the board underneath the lifted leather (PVA) and continuously pressed down the PC4 paper until it stuck. Then I placed silicon release paper between the PC4 paper and the lifted leather (to prevent moisture from being introduced to the leather too soon), and flipped the book over to dry under the weight of the text block. I did this to all four books, then repeated the process with the other side. Then I glued down the lifted leather (PVA). Once all the spine pieces were attached to both covers, I glued down the head and tail turn-ins. When those had dried, I glued down the lifted endpapers (PVA), and then covered the hinge with a strip of Japanese tissue (paste).
After all the inside hinge repairs were done, I glued the remaining original spine pieces to the new PC4 spine (PVA) and consolidated the leather with Klucel G. Next I repaired the corners and put Japanese paper along the leather at the joint and along the edges of the original spine pieces. I used two different methods for this as well. On two books I used morike (top), which had to be cut to shape with a water pen, but was already a similar color and therefore easier to tone. On the other two I used dry tear strips (bottom), which allowed for fast and easy application, but proved more difficult to tone. Finally, I rubbed some SC 6000 over the joints to add some shine to the toned Japanese tissue and prevent the acrylic from cracking with use (Winter 2009).