Repair paper tears with clear document-repair tape. To repair a tear, use scissors to cut two sections of tape that are just longer than the tear. Place the tape on both sides of the tear, and smooth and press it down with a bone folder. Use scissors to trim excess tape beyond the edge of the paper.
Reattach pages that have separated from the inner spine. Open the book to the where the separated page belongs. Extrude a thin line of acid-free glue along the inner spine. Stick the page in place. Stick pieces of wax paper on either side of the page to prevent the glue from oozing up and causing pages to stick together. Once all pages are glued in and lined with wax paper, close the book and place a couple of heavier books on top to secure the book closed. Allow the glue to dry according to the dry time on the bottle.
Mend tears in the book cover with linen book-binding tape. Use scissors to cut a section of tape that is just longer than the tear. Remove the backing to reveal the adhesive on the tape, and press the tape onto the tear at the inside of the book cover. Smooth and press down the tape with a bone folder. Use scissors to trim any excess tape sticking out beyond the edge of the cover.
Reattach the cover if it has separated from the spine. Use a small paint brush to apply an even coat of acid-free glue to the book spine. Press the cover into place and wrap rubber bands around the book to firmly secure the cover while the glue dries.