Generally, handling and use heightens the risk of damage to your materials, be it through neglectful handling (e.g. touching photo emulsion with bare hands) or irresponsible operation of access equipment. This is a risk posed by patrons and staff alike, intentional or not.
One of the easiest areas to implement protections for collections is through careful handling and sensible collections care. The unfettered use and handling of materials heightens the general risk of damage--be it through neglectful handling (e.g. touching photo emulsion with bare hands) or irresponsible operation of access equipment. Whether intentional or not, this is a risk posed by patrons and staff alike.
Examples of neglect, mishandling, and mismanagement include:
The use of additional copies for reference or display purposes is highly recommended, particularly if the item is an original or valuable. This provides broader access to the content while also protecting the original document from user wear and tear or environmental factors.
Recommendations for care of original object:
To learn more about best practices for use and access, including resources for creating digital surrogates, see Use & Access in the User-Manual.
Store vertically with dividers between each slide. May also be stored horizontally (flat). Roll film may remain rolled or may be segmented for more uniform, flat storage. Enclosures and folders may be stored in hanging files or archival storage boxes.
Monochrome transparencies should be protected from light exposure and stored in a cold, dark, dry environment.
Acid-free enclosures and/or folders strongly advised. Due to the inherent acidity of cellulose nitrate and acetate, storage in a buffered (alkaline) enclosure is recommended. Each slide should have its own enclosure to protect it from dust, handling damage, and changes in environmental conditions. This enclosure may be a paper (conservation-quality, acid-free) or plastic (uncoated polyester, polyethylene, polypropylene, cellulose triacetate) sleeve, envelope, or wrapper. Position photo image material away from seams in paper enclosures. Such seams (if any) should be on the sides of the enclosure, not down its center. Wood cabinets should be avoided. Enameled steel, stainless steel, or anodized aluminum are preferred for storage equipment. All storage materials should pass the Photographic Activity Test (PAT) as specified in ISO Standard 18916:2007.
If your item has any kind of labeling on the container, the item itself, or any related material, we highly recommend that you return to the Basic Info section and enter this information in the appropriate field(s).
Cellulose acetate film with softening binder is at higher risk for physical damage as the gelatin emulsion pulls away from the base. Damage can include scratches and torn film, although film with a polyester base does not tear easily. Film can be a very fragile medium if there are tears, perforations, or other forms of mechanical damage.
Nitrate: Nitrate film deterioration is exacerbated by either a humid or dry environment. In a humid environment, the emulsion may soften and become sticky; in a dry environment, the film becomes brittle. In the final stage of deterioration, nitrate film forms a solid mass that cannot be separated or handled safely. Nitrate deterioration can be identified by the acrid, sharp odor as nitric and nitrous acids are released. These acidic vapors are damaging to surrounding objects, so deteriorating film must be evaluated to determine whether it should be discarded. See Nitrate Decay in the Film Decay section below for more information.
Acetate: Cellulose acetate film is susceptible to vinegar syndrome, which causes the film base to shrink and the gelatin emulsion to pull up in folds. A strong vinegar odor is a telltale symptom in later stages of deterioration. Acetate deterioration is accelerated by humid conditions. See Acetate Decay in the Film Decay section below for more information.
Polyester: Polyester film is inert. It is considered archival and has a life-expectancy of 500+ years under proper storage conditions.
The gelatin binder of a photographic emulsion is an especially good nutrient for mold. If your item is exhibiting white or brown patches or if you see a lattice-like growth along the edges, you are most likely viewing mold. Negatives stored in hot, humid environments (generally above 65% relative humidity) are most vulnerable to mold, mildew, and fungus contamination. Mold will typically damage the edges of a photographic material first. If mold has eaten into the emulsion, the item will be noticeably and irreparably damaged, exhibiting feathery-like distortions or dull spots on the projected image. Mold can be removed through cleaning and then storing the items in a cold, dry environment, but this should be done responsibly.
Pests like insects and rodents tend to like paper and textile materials more than plastic-based materials. That said, pests can still do damage. Insects can be attracted to the organic components of emulsion (i.e. gelatin). When assessing the exposure of your collections to pests, it is necessary to look not just at the materials themselves and their containers, but also at the larger environment. Insects and rodents tend to leave droppings in areas they inhabit. Insects tend to leave behind a substance called frass, which is the undigested fibers from paper. If you see droppings and/or frass in the storage area, it is a strong sign that your materials are being exposed to pests. Small, irregular holes on paper-based enclosures are also a sign that pests have attacked your materials.
Some tips for reducing your materials' exposure to pests are to refrain from eating anywhere near your collections materials. Crumbs draw pests, so keep food far away from your collections. Another tip applying to both pests and mold is to be cautious about donated materials when you receive them. Pests and mold can hitch a ride into your facility on these materials, so having a good, clean staging area where you can inspect donated items for, among other things, pest and mold evidence can help you reduce your storage environments' exposure to both.
B&W film slides may be on a nitrate, acetate, or polyester base. Acetate film may be identified by "SAFETY" edge markings or manufacturer notch codes. Polyester film is not usually marked, but it may bear "Estar" or "Cronar" edge markings. If you are having difficulty identifying your film base, jump to the Film Base Materials in the Collection ID Guide.
Deterioration of the film support varies depending on the type of plastic.
Acetate: Cellulose acetate film is susceptible to vinegar syndrome, causing the film base to shrink and the gelatin emulsion to pull up in folds. A strong vinegar odor is a telltale symptom in later stages of deterioration. Acetate deterioration is accelerated by humid conditions.
Polyester: Polyester film is inert. It is considered archival and has a life-expectancy of 500+ years under proper storage conditions.
Nitrate in the beginning stages of decay will have a noxious odor, like "dirty socks." Be careful when testing film for odor—open the film can away from your nose and face so you are not exposed to irritating or toxic fumes and particles. You should be able to detect an odor without having your nose in close contact with the film.
The following is a guide to rating nitrate breakdown:
Deterioration Starting. As a guide to assigning a value, nitrate in this condition would have no decay or be in the earliest stages of decay. Due to the age and inherent vice of nitrate film, almost all of it will suffer from some decay. If the film is flexible, with little to no damage to the emulsion or image, it should still be considered as being in the early stages of deterioration. If you have nitrate film, PSAP recommends that you do not select "No deterioration," no matter how good the condition of the film appears to be.
Actively Deteriorating. Nitrate in this condition will exhibit emulsion damage and will most likely include image-area damage. It will have a noticeable noxious odor and may stick to itself as it is unwound. Nitrate film requires special care in handling, and a film with the "Actively Deteriorating" designation will imply some damage. As such, this film will need to be sent to a vendor for content retrieval and transfer.
If you discover you have degrading nitrate film, store it in a cold to freezing environment as soon as possible to prevent the risk of fire and to avoid further damage to the film and surrounding materials. If you do not have the resources to properly and safely handle nitrate film, contact an institution that may and strongly consider transferring the film to that institution. DO NOT throw away nitrate film! Not only could it be a valuable and unique resource, but nitrate is considered a hazardous material and must be disposed of properly.
Critical Deterioration. Nitrate film in this condition is extremely dangerous and volatile. The content of the film is most likely irretrievable as the film has congealed into a solid mass or has disintegrated into a brownish powder. Do not dispose of the film by throwing it in the garbage! You will want to contact a local HAZMAT disposal center to safely remove and dispose of this material. If you are unsure how to do so, try contacting your regional waste disposal office for further advice.
One of the key signs that an acetate film is degrading is the presence of a vinegar smell. This degradation results from the chemical breakdown of the acetate into acetic acid and is known as "vinegar syndrome." When the film can is opened, the odor can be very strong and unmistakable.
Although the vinegar odor is often the most obvious sign that an acetate film is degrading, it is not the only sign. Acetate film that is degrading becomes brittle. The film loses its suppleness and does not gently curve around the core or reel; instead, the film appears jagged or "spoked." The film base will also shrink. To help prevent or slow acetate decay, you can place molecular sieves in your film cans. These desiccants will help absorb acetic acid and moisture in a sealed film can.
The PSAP has also adapted the Image Permanence Institute's A-D Strip scoring method to rate vinegar syndrome in acetate film. These strips, developed by the Image Permanence Institute, change color based upon the level of acidic vapor detected. A-D strips are an excellent way to score and monitor vinegar syndrome; they can give you a finer level of assessment beyond visual and olfactory cues. Using A-D Strips in conjunction with the PSAP can make your vinegar syndrome assessment much more accurate. For more information about A-D Strips, click here: https://www.imagepermanenceinstitute.org/imaging/ad-strips.
The following is a guide to rating acetate decay (vinegar syndrome):
No Deterioration. This film is suffering from no acetate decay.
Deterioration Starting. Acetate decay is starting. This film should be moved to cold storage, if possible, and monitored. The film is flexible, with little (less than 1%) to no apparent shrinkage. There may be a very faint vinegar smell.
Actively Deteriorating. This film is actively deteriorating. It should be moved to cold storage, if possible, and duplicated. The film will have a stronger vinegar odor and may exhibit shrinkage (between .8 to 2%). The film may be able to be accessed or read in-house by an experienced technician using maintained and functioning equipment. The film will also exhibit some waviness along the edges; it may curl slightly and resist lying flat.
Critical Deterioration. This film is exhibiting shrinkage and warping. It may be difficult or impossible to handle the film without damaging it. The film should be frozen if possible. The vinegar odor is unmistakable. (You should exercise caution when opening all film cans and avoid sticking your nose into the can—you could be in for a very unpleasant and potentially dangerous surprise!) The emulsion layer looks cracked, and it may already have separated from the film base. The film is very brittle and inflexible. It may appear to be "spoking," in which the film pack does not look rounded but appears more angled. White powder may be visible on the edges of the film. In this stage of decay, the content may be unrecoverable. Acetate-based film in critical condition often cannot safely be read or played back in-house—if it can be at all. However, depending upon the flexibility of the film, the condition of the emulsion and image area, and shrinkage, a highly qualified vendor may be able to recover the content.
In order to slow or stop acetate decay, it should be stored in cold to frozen conditions (32–40°F and less than 32°F, respectively). Once the decay starts, it cannot be reversed. If a film is discovered to be acidic and succumbing to vinegar syndrome, it should be separated from other "healthy" films as it can "infect" the other films.
Silver-gelatin images often exhibit silver mirroring due to oxidation, causing the silver particles to rise to the top of the gelatin layer. This is typically more acute along the edges and in darker areas of the image. Image fading is first and most apparent in highlights. Discoloration (yellow-brown) and fading in highlights, at edges, or across the image is often a symptom of air pollutants or poor storage materials.
If you are aware of airbourne pollutants in the space that your material is housed, be certain to check for discoloration and silver mirroring. Airbourne pollutants initiate chemical reactions that may stain and degrade support/base materials and accelerate the fading, staining, or loss of photographic and print/writing media. Sulfur dioxide, hydrogen sulfide, and ozone cause oxidation in silver images and contribute to silver mirroring or yellowing.
For more information on identifying and managing silver-gelatin emulsion on plastic supports, see the Collection ID Guide's profile on Silver Gelatin Negatives.