Our 100% Rag, Museum Board is made of 100% cotton fiber and is acid-free. The board is solid color through out. 1, 2, and 4-ply are sold and packaged in cases of 25 sheets. The 8-ply sheets are sold and packaged in cases of 10 sheets. All of our rag board cases are UPS shippable. Thickness conversions for museum board: 1-ply = 1/64", 2-ply = 1/32", 4-ply = 1/16", 8-ply = 1/8"