Most likely caused by acidification of the paper as a result of sulfuric acid used to bleach the pulp prior to the manufacture of the paper. Not much can be done to alleviate the problem. Also known as signatures or quires. As sheet of printed paper come off the press, it is folded to form a group of pages. At this point it is blissfully united with other similar groups which are then sewn or glued together to form the bulk of the book.
All edges gilt.
Half title page . One of the free end papers which generally have the title of the book or state if the books is in a series. The inside of the front and back covers where the joint is. Hinges Starting . This term means basically the covers are starting to separate from the pages of the book.