We offer the largest selection of 100% cotton museum- quality mat boards in the industry with the advantage of incorporating MicroChamber Technology. Available in a broad range of subtle and classic colors, this material is constructed of four equal plies and offers superior rigidity and strength. ArtCare boards meet the regulations of ANSI/ NISO Z39.48-1992 (Permanence of Paper) and pass the Photographic Activity Test (P.A.T.). They are acid-, lignin- and sulfur-free. No optical brighteners are used in the manufacturing process. ArtCare Photorag is completely non- buffered. It is sold in cartons of ten sheets 32 x 40.