Acid-Free:  Technically, materials having a pH of 7 or higher are considered to be acid-free. Acids are evil as far as framers are concerned. Cardboard, for instance has a very high acid content, making it unsuitable for conservation framing, or any framing really. Acids cause papers to become stained and brittle over time.

Some regular matboards claim to have acid-free core and backing paper. Making it completely free of acid, right? Well, no. While this is better than nothing, the boards still contain lignin which down the road results in a more acidic board. These regular boards are buffered with calcium carbonate to neutralize the existing acids, but this buffer will be overwhelmed as time goes on. Also keep in mind that the surface paper is not acid-free and outgasses pollutants, and dyes are used for coloring the surface which fade quickly compared to pigments.

Conservation-grade boards are completely acid-free in the commonly thought of sense of the word.

Alpha Cellulose - This is plant (usually wood) pulp that has been purified, removing lignin and other potentially damaging substances, leaving an almost pure cellulose which is of a neutral pH.

Alphamat Alphamat is a brand name for a conservation matboard made by Nielsen & Bainbridge. It is composed of alpha cellulose, the surface paper is colored using light-fast pigments, and the board is part of the Artcare family of products utilizing MicroChamber Technology.

Alum This is a chemical that is sometimes used to set dyes and sizings (adhesives) in papermaking. Alum is not an archival substance and is acidic. None of the conservation matboards or conservation materials include alum.