Acid-free and pH-buffered materials are both used in conservation and archival practices to protect artworks, documents, photographs, and other valuable items.
While they share a common goal of preserving materials, there are differences in their composition and functions:
1. Acid-Free:
- Acid-free materials are pH neutral or slightly alkaline, with a pH level of 7 or above.
- They are manufactured without acidic components, such as lignin and sulfuric acid, which can cause deterioration over time.
- Acid-free materials are recommended for long-term preservation because they do not contribute to the degradation of the stored items.
- Common acid-free materials include paper, mat boards, and storage boxes.
2. pH-Buffered:
- pH-buffered materials are designed to maintain a stable pH level over time, typically within the slightly alkaline range (pH 7.5 to 9).
- They contain an alkaline reserve, usually in the form of calcium carbonate or magnesium carbonate, which helps neutralize any acids that may be present.
- pH-buffered materials offer added protection against external acidic environments and fluctuations in humidity and temperature.
- While pH-buffered materials provide enhanced stability, they may not be necessary for all types of materials and storage conditions.
While both acid-free and pH-buffered materials offer protection against deterioration, pH-buffered materials provide an additional safeguard by stabilizing pH levels and neutralizing acids that could potentially harm stored items. The choice between the two depends on the specific preservation needs and environmental conditions of the items being stored.