Placing a backing behind or in the center of your paper product, then putting it inside a polybag helps prevent the item from crimping or wrinkling gives it rigidity. If the board is acid-free, it neutralizes acids in the paper and in the atmosphere. If the board is acid-free and buffered, not only is the acid in the item neutralized, but acids in the atmosphere are prevented from entering the stored item.

We stock 5 grades of backing boards:
1. CHIPBOARD - pH neutral board contains acid and is not meant for long-term storage. It is .030" thick and an excellent choice for short-term storage. White on one side. SUPER economical.
2. 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 point board for intermediate to long-term storage. White on both sides.
3. SUPER ACID-FREE  - Our .40 point thick board is off-white, 100% Alpha Cellulose board and buffered with calcium carbonate, which keeps the board from breaking down (indefinitely). Acid-free (alkaline 8.0-9.0), lignin-free, contaminant-free. Suitable for conservation. Meets Library of Congress Archival Standards for indefinite storage. 
4. CORRUGATED  CARDBOARD is .1875" thick (C-Flute, white on 2 sides). It contains acid but is a popular choice for a backing board because it is rigid and economical. Use for short-term storage or display. 
5. ARCHIVAL CORRUGATED CARDBOARD - Is Museum Grade Archival. The board is .125" thick, B-Flute. "Banner Blue". It is acid-free and lignin-free, buffered with a 3% calcium carbonate buffer. Use for indefinite storage.