Buckle and Edgewave.

A piece of buckled film

Buckle is a condition in which it is impossible for the film to lie flat due to some part having shrunk more than another. This usually shows as the film forming an "arch" if the edges have shrunk more than the middle, or as "edgewave" if the middle has shrunk more than the edges.

Very dry, low humidity storage conditions affect the outside of the reel (i.e. the perforation area) before the centre, producing "arching" as the edges shrink more than the middle.

Edgewave, when the middle shrinks more than the perforated margin, the edge becoming wavy, is usually caused by projector heat in the picture area shrinking the centre more than the margins.

Edgewave can also be caused by some local "polishing" treatments designed to reduce scratches on the base surface. Some treatments affect only the picture area and cause this to shrink. These treatments should be avoided.

If a film is buckled or contains edgewave, it can be difficult to contact print because the film is not in perfect contact with the print stock. In general, these films print best on flat gate step printers such as the Debrie Matipo.