Glue traps are necessary in perfect bound books.
On your proposals, sometimes you will see a note from us that says, “Covers must overhang insides by minimum 1/8”. The overhang incorporates a glue trap.
A glue trap does exactly what the name says; it traps the glue from escaping. When a book is perfect bound, we apply glue to the entire spine and side hinges of the book.
The glue is applied from head to foot along the spine. When the cover is attached to the book block, the glue will ‘squish’ out from the head and the foot. If the cover overhangs the book, then the glue will be trapped within the area needed to stick the insides to the cover.
If the cover does not overhang the book, the glue will squish out and damage the machinery. In addition, the excess glue that is not trapped might damage books during the run.
Overhang is absolutely necessary when you perfect bind a book.
Below is a basic 2up layout of an 8 ½” x 11” cover on a 19” x 25” press sheet.
Note that the spine has the ink and coatings knocked out as well in order to allow better adhesion of the book block. In addition to having the spine knocked out, also maintain a margin of ¼” on either side of the spine to allow room for hinge scores.
To find out more about glue traps, contact Pacific Bindery Services.