Where a sheet material (e.g. paper) has been intentionally bent over on itself, often causing the fibres of the material to break or become damaged and hence more susceptible to further deterioration. For example, a folded piece of paper may eventually tear along fold marks.

A hand-painted fan design has been folded in half, causing damage to the paper fibres and the image. Photo courtesy of Alice Cannon. 


Folding has caused a permanent mark in this decorative textile border. Photo courtesy of Alice Cannon.