Enclosures
It is important to separate photographs and negatives from from textual materials unless each photograph receives an individual plastic enclosure. In order to maintain provenance and original order, replace the items with neutral pH separation sheets and copy images.
Ideally, each photograph should be stored in its own sleeve or folder for protection from damaging components of other photographs. Prints and negatives should always be stored in separate enclosures. These enclosures may be made of of either paper or plastic.
PaperPaper enclosures that come in direct contact with photographs should follow ISO 18902. Thus, they should have an alpha-cellulose content greater than 87% and be free of groundwood, alum rosin sizing, and metal particles.
If paper envelopes are chosen, those with thumb tabs should be avoided as they encourage users to pull the photo from the sleeve instead of lightly squeezing the edges and shaking or taping the photograph out. The emulsion side of a photograph should face away from the envelope's seam to avoid contact with the adhesive. Seams on paper envelopes should be along the sides and not through the center. There is disagreement over the effects that buffered paper may have on certain photographic processes. Its alkaline nature can neutralize acids as they form. According to some sources, buffered paper should not be used with color images, cyanotypes, or albumen prints. However, it is recommended for nitrate and diacetate film negatives, brittle prints, and photographs on acidic mounts. More recent literature indicates that buffered paper is safe for all types of photographs as the pH of paper will decrease over time. The ideal paper envelope is buffered, seamless, and made of four flaps that create a pocket. However, this style is more expensive than seamed enclosures and adds more bulk and weight to the collection. |
PlasticPlastics have the potential to build up static electricity which attracts dust and dirt that may abrade the surface of images. Static electricity can also exacerbate the problem of flaking and lifting emulsions.
Because plastics can be sealed with heat instead of adhesives, the problem of seams is avoided. The ideal plastic envelope is an L-sleeve which is sealed on two sides. This allows for easy insertion and removal by archivists but prevents the researcher from touching the image. SelectionUnfortunately, no one enclosure is ideal for all photographic materials. Instead, archivists must choose housing based on the photographic process, format, condition, and value of images.
While storing each image in an individual enclosure is optimal, this may not be financially possible for all repositories. Instead, it may be necessary to create priorities which ensure that photographs with the greatest value and need receive the housing that they require. Photographs that have high value or are in fragile condition as well as negatives should be prioritized for individual enclosures. Stable photographs of low to moderate value as well as copy prints may be safely stored as a group within a folder. If possible, interleave with archival quality paper. At the least, small-format paper prints, cased images, negatives, and oversized photographs should be stored separately. Original and duplicate photographs should also be housed and stored separately for both security and preservation reasons. Once enclosed in envelopes and/or folders, photographs should be housed in paperboard boxes low in lignin content and with an alkaline reserve. Images may be stored vertically or horizontally but glass plate negatives should always be stored upright to prevent breakage. Flat storage is preferred for larger formats or photographs in poor or fragile condition. |