We stock 5 grades of Poster Backing Boards: 1. Standard Acid-free is acid-free all the way through. Acid-free board can trap migrating acids in paper and neutralize it. Use our .028' thick board for intermediate to long-term storage. White on both sides.
2. Super Acid-free - Museum Grade Archival. Our .040" thick board is all white. It is acid- and lignin-free and buffered with a 3% calcium carbonate buffer.
3.Corrugated is either .0625"thick (E-Flute, white on two sides) or .125"thick (B-Flute, white on 2 sides). It is a popular choice for a backing board because it is rigid and economical.
4. Foam Board - Museum Grade Archival. This board is an indefinite-term, archival board. It has a polystyrene foam core (making it ultralightweight) with a laminated white, smooth facing. It is buffered with 3% calcium carbonate and is acid-free with a pH of 7.5-8.5. It is either .125" or .1875" thick, super rigid.
5. Archival Corrugated - Museum Grade Archival. This board is.125" thick, B-Flute, "Banner Blue" corrugated cardboard. It is acid- and lignin-free and buffered with a 3% calcium carbonate buffer. Safe for indefinite-term storage.