Frequently Asked Questions: Preservation

Suitable protective enclosures for photographic prints and negatives are made of plastic or paper that meet certain specifications:

• Paper enclosures must be acid-free, lignin-free, and are available in both alkaline buffered (pH 8.5) and unbuffered (neutral, pH 7) stock. Storage materials must pass the ANSI Photographic Activity Test (PAT) which is noted in supplier's catalogs. Buffered paper enclosures are recommended for brittle prints that have been mounted onto poor quality secondary supports and for deteriorated film-base negatives. Buffered enclosures are not recommended for contemporary color materials. Paper enclosures minimize unnecessary light exposure; are porous; easy to label with pencil; and are relatively inexpensive.

• Suitable plastic enclosures are made of uncoated polyester film, uncoated cellulose triacetate, polyethylene, and polypropylene. Note: Photographic emulsions may stick to the slick plastic surfaces of these storage materials at high relative humidity (RH). Plastic enclosures must not be used for glass plate, nitrate, or acetate-based negatives.

Prints of historic value should be matted with acid-free rag or museum board for protection. Adhesives should not touch the print. Matting should be done by an experienced framer or under the direction of a conservator.

Store all prints and negatives (whether matted or in paper or plastic enclosures) in acid-free boxes. If possible, keep negatives separate from print materials. Store color transparencies/slides in acid-free cardstock boxes or metal boxes with a baked-on enamel finish or in polypropylene slide pages. For more information about storage of negatives, see Motion Picture Film.

Protect cased photographs (e.g., daguerreotypes, ambrotypes, and tintypes) in acid-free paper envelopes and store flat; keep loose tintypes in polyester sleeves, or, if flaking is present, in paper enclosures.

Storage of family photographs in albums is often desirable and many commercially available albums use archival-quality materials. Avoid albums with colored pages and "magnetic" or "no stick" albums.