Archival Methods 2-Ply Bright White 100% Cotton Museum Board contains 25 boards that measure 17 x 22" each. The board is a high-quality mat board used for many fine print and document projects. Whether for traditional print or digital technology, this board will provide a solid, acid-free backing that is perfect for display purposes. It can also be used for small mat cutting where, for example, a 2-ply board will provide a 1/32" separation between the work and the glazing.