printing distortions

The uneven shape of leaves in a hand-printed book that result from printing on damp paper with a soft blanket in the tympan of the press. This tends to stretch the paper around the edge of the type area, and this ‘extra’ paper is accommodated in horizontal undulations across the centre of the type area and curved or angled undulations across the corners. If the book has deep undulations and is heavily beaten or pressed, these undulations may be turned into pleated creases, sometimes locking groups of leaves together.