Edge gilding of a book serves a three-fold purpose. Originally books were gilt only on the top edge. Books on a shelf collect dust. Dust will not stick to a gold surface. So a book can be taken from a shelf and dust can simply be blown off with a breath of air. Additionally, sealing off the page edges of a book provides a barrier against the moisture and air pollution, which can alter the pH in the paper, causing it to become discolored and brittle at the edges. In the decorative sense, if done correctly and with “taste,” edge treatments can either add the luster and beauty of gold to the binding of a book. Or, if gold isn’t part of the binding’s design, the page edges can be coated with any designated color of gauche paint with contrasting speckle added, and this will provide a moisture barrier as described above.