One main purpose of a matte is to be replaceable.
Another is to keep the surface of the print from contacting glazing material in the frame.
If the mat overlaps the print, there may well be, in time, light- or contaminant-induced differences between the covered and exposed parts of the print. Archival materials are intended to prevent the latter, but only storage in the dark will prevent the former. A "floating mount" as described by Ralph Lambrecht is one solution to this problem. Properly done, the signature can be on the mount rather than directly on the print, and will not be lost in re-matting.
(Yes, I know that there are reams of controversy with respect to dry mounting versus hinging, but this thread is about the merits of easels, right?
Another is to keep the surface of the print from contacting glazing material in the frame.
If the mat overlaps the print, there may well be, in time, light- or contaminant-induced differences between the covered and exposed parts of the print. Archival materials are intended to prevent the latter, but only storage in the dark will prevent the former. A "floating mount" as described by Ralph Lambrecht is one solution to this problem. Properly done, the signature can be on the mount rather than directly on the print, and will not be lost in re-matting.
(Yes, I know that there are reams of controversy with respect to dry mounting versus hinging, but this thread is about the merits of easels, right?