Regardless of the sewing method used, the sewn book must be "knocked up" to be square at head and spine. By hammering along the back edges, the expansion resulting from the sewing can be reduced. The spine is glued with a thin hot glue diluted with some insecticide such as DDT. The book again is "knocked up" to round the spine and the spine, line. Preparation of cover boards for the book case requires exact measurements. To prevent the deposition of colouring matter of the boards from showing through the end papers, the boards are to be lined up and marked for sewing and for fixing tapes. The board is then attached to the book and pressed and the glue is let to dry.
Sheets before and after the text of a book are called endpapers and they may or may not be decorated. Marbling is the classic type of decoration used and commercial binders often use maps, engravings or pertinent photographs for endpaper illustration. The endpapers perform a protective function and thus require leaves for good quality paper.