Here is an easy repair that you can make at home to a book with a broken binding. If the book is covered with book cloth, and the cover along the spine is torn at the bottom and top, cut it in the middle, between the two tears so the spine piece becomes a flap. Now take a piece of bookbinding cloth the same color as the book cover-book cloth can be purchased at a specialty shop or an art supply stores-and cut a narrow piece the same length as the spine flap and approximately one inch wide.
Now gently lift the book cover along the back edge. You can do this with a tool, such as a pallet knife. You must work slowly, lifting the cover along the back edge, about 1/4 inch in from the spine. Once this is lifted and the cover cloth is scraped clean of any cardboard residue, trim any tiny threads sticking out from the spine flap or along the cover piece that you've just lifted with the knife.
Now it is time to use a glue that is made especially for bookbinding-also available where you've purchased the cloth. Use a brush to paint an narrow edge of glue along the strip of book cloth you've just cut. Now attach this piece to the edge of the cardboard that you have uncovered with the knife. Make sure that the book cloth matches up with the top and the bottom of the cardboard and rests evenly in from the edge from top to bottom. Do not place it against the folded back cover, but in from the edge enough to be secure.
Smooth this down with a bone folder. Now brush the remaining exposed area of the front cover with glue and press it down with your fingers over the new piece you've just glued down. Now smooth this part of the repair with the bone folder. Cover with waxed paper and weight it with a stack of books or a brick for about fifteen minutes, or until it dry.
Once this is dry, bring the loose spin over the new flap and see how they fit together. If you need to trim the repair piece a bit, do it now. Make sure you remove an even amount from top to bottom. Now spread glue on to the replacement piece and flap the loose spine over, smoothing the joined pieces with your fingers. You may or may not need the bone folder to complete the spine repair, although the tip works nicely for pressing in tiny bits of fabric that are in need or tucking or pressing.
Let the book dry for twenty-four hours. Your repair is complete and the book as good as new.