Jones on Sewing for Bookbinding: "The book shown in Figure 6.4 has seen several years of use, and the impact of this wear is quite visible. Repeated flexing of the fold where the book front meets the spine has torn some of the surface fibers. Should this crease ever begin to tear, it would be a simple matter to thread linen tape through the sewing and glue it to the front and back covers in order to reinforce the spine and hinges. The photo shows no wear on the threads, and the torn fibers along the crease are very clean; this is because the book has been protected by a dust jacket since it was bound."