We offer the largest selection of 100% cotton museum- quality mat boards in the industry with the advantage of incorporating MicroChamber Technology. Made from 100% pure cotton pulp, featuring top to bottom cotton fiber, and subject to the most rigorous quality controls, Alpharag Artcare meets or exceeds all industry standards for paper permanence. Alpharag Artcare incorporates the patented and proven MicroChamberÂ® technology to actively protect art and photos from airborne pollutants and acids, thereby offering a preventative conservation protection unachievable with any other rag product. This material is constructed of four equal plies and offers superior rigidity and strength. All boards meet the regulations of ANSI/ NISO Z39.48-1992 (Permanence of Paper) and pass the Photographic Activity Test (P.A.T.). No optical brighteners are used in the manufacturing process. Natural White has non-buffered outer plies and is offered in cartons of 10 sheets in 32 x 40 and 40 x 60.