Mounts
There was no reason for artists to mount drawings while they were in use in the workshop, but collectors adopted the practice at an early date, and it is ubiquitous today. Mounts are intended to protect valued sheets in boxes, albums, or in frames. They could take the form of single heavy sheets of paper with a few decorative lines, elaborate ornamental designs, or the hinged double layers of paperboard that are in common use today.

 

by Michael Miller
Information supplied by: http://www.nyu.edu/classes