Paper that contains no free acids, thus providing greater permanence and durability; the term does not necessarily imply that the paper is alkaline-buffered. Acid-free paper is typically produced from cotton linters, rags, esparto grass, or chemical wood pulp which minimizes the potential for acid and/or lignin in the pulp. Acid-free paper may also contain a buffering material to maintain a pH in the neutral to slightly alkaline range. This helps scavenge any acidic materials formed by bleaching residues, sizes, degradation products, or air pollutants.
