Hierarchy classification:

1. top of the aat hierarchies
2. Materials Facet
3. Materials (hierarchy name)
4. materials (substances)
5. [materials by form]
6. [materials by physical form]
7. [fiber and fiber by product]
8. [fiber by product]
9. paper (fiber product)
10. [paper by composition or origin]

Anotations

Scope note:

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.