Mat Board
A card window placed over a print inside a frame, separating it from the glazing and providing visual space.
Measured in
mm
In depth
The mat's structural job is to hold the print away from the glass, since contact allows moisture to transfer and the emulsion to stick. Its visual job is to give the image breathing room. Board must be acid-free and lignin-free, as ordinary card will burn a brown line into the print within a few years.
Examples in practice
An acid-free mat holds the print 2 mm clear of the glazing, preventing any contact in humid conditions.