JAS White Core Mount Board is a 1.5mm thick acid-free mount board which weighs 850gsm. It consists of three layers: a 110gsm paper surface which is available in 16 colours; a 1.1mm thick, fully coated, bleached paperboard core which is acid free and which is considered sufficiently inert to be used in direct contact with documents; a backing layer of white chlorine- and acid-free cellulose paper.

These mountboards are not fully lightfast and should not be stored in direct sunlight, though they will display good colour-stability if stored out of direct sunlight. The front surface paper and the white paperboard core accords to ISO 6588, while the back paper accords to ISO9706. It is the back sheet, which is most fully in contact with the artwork, that has the highest archival specifications.

These pre-cut mount boards measure 30 x 40cm along the outer edge, with an aperture of 20 x 30cm.