In chemistry, a substance capable of forming hydrogen ions when dissolved in water.
Acids can weaken cellulose in paper, board, and cloth, leading to embrittlement.
Acids may also be introduced by migration from other materials or from atmospheric pollution. Also see pH and Acid migration. In chemistry, materials that have a pH of 7.0 or higher. Sometimes used incorrectly as a synonym for alkaline or buffered. However free of acid a paper or board may be immediately after manufacture, over time the presence of residual chlorine from bleaching, aluminum sulfate from sizing, or pollutants in the atmosphere may lead to the formation of acid unless the paper or board has been buffered with an alkaline substance.