(Buffer) In chemistry, a solution or material which contains both a weak acid and its conjugate weak base such that the addition of other acid or alkali causes only slight changes in the pH; also, the alkaline reserve contained in paper based materials in order to counteract acids that may form in the future.

Drives an acidic or alkaline solution to neutral.

An alkaline substance, usually calcium carbonate or magnesium carbonate, occurring naturally in a water supply or purposely added by the papermaker to help counteract acidity in paper.

An ingredient which stabilizes the pH of a mixture. Useful in stabilizing formulations containing very acidic (low pH) or very alkaline (high pH) ingredients.

A chemical used to regulate pH. Buffered mat and mounting boards typically have calcium carbonate added to the paper to achieve a pH of about 8.5. This is sufficient to counteract migrating acid from decomposing lignin in the wood frame if the mat has at least a two inch border.