Double Fan Adhesive Binding
Double fan adhesive binding is a type of adhesive binding where the back edge of each leaf is exposed to 1/16" or less of adhesive. The margin is exposed on both sides of each leaf by clamping the textblock on a vise-like press and then pushing against the textblock, first in one direction, then the other, thereby fanning or separating the edges of the leaves. Double-fan adhesive bound books will open flatter and preserve more gutter margin than an oversewn volume. However, certain types of paper (such as coated paper) do not hold adhesive well, and, with wear and tear, the pages can come loose.