- About Archives
- About SAA
- Careers
- Education
- Publications
- Advocacy
- Membership
PRELIMINARY DRAFT
In this introduction to the basic care of photographic collections we have emphasized photographic processes used from 1920 onwards assuming that the bulk, if not all your collections will be from this time period. Be aware that if your collection includes earlier photographs please consult one of the other online resources listed at the end of this page since preservation and identification of nineteenth century photographs can be quite different from the twentieth century due to vastly different processes used.
One repeat caution which applies to all work on archival objects: Do not do anything to an item which you cannot safely and totally undo.
Types of Photographic Prints
During the twentieth century, photographs have been printed on a variety of bases. For many years, both color and black and white prints were predominantly made on a heavy paper base. Some papers produced a matte finish, others a glossy finish. Today resin-coated paper is the predominant base. Resin-coated paper is, however, not really paper but a polyester base. Because the bond between the polyester of the base and the thin layer of emulsion containing the silver salts is not as secure as that bond in real paper based prints, the emulsion may start separating and when handled may begin breaking or chipping away. If this occurs on prints for which you do not have negatives, you should consider having copy negatives made as soon as possible. The more the prints are handled, the more damage that can occur, resulting eventually in the loss of the image. Because the oils on your fingers can permanently damage photographic prints it is essential you wear clean cotton gloves when handling photographic prints. Gloves manufactured for this purpose can be obtained from the vendors listed below. For preservation of digital images please consult the electronic records page.
Identifying and Labeling
Clearly the more information you can attach to your prints concerning the event and people pictured in a print, the more useful the print will be to your patrons. Photographs mounted in a scrapbook may or may not have any identification along with the prints. If you have an opportunity of having the donor or some other member of the community identify photographs, make a photocopy of the page on acid-free paper and write identifying information on the photocopy. If no photocopier is available, writing on a piece of acid free paper works just as well. Frequently, photographs have some identification written on the reverse of the print. Resin-coated paper cannot successfully be written on with pencil, so most use ink. Ink, however, usually contains some acids which will damage the print over time. Any writing on the reverse of a print will cause indentations in the paper and damage the bond between the emulsion layer and the stratum. It is best to write the information on the envelope or other enclosure. Some repositories write the identification number on the print but many will only write it on the enclosure to help preserve it.
In the twentieth century, you will most likely encounter film based negatives, so we will limit our discussion to these only. Film based photographic negatives have a variety of bases. Two types of bases are unstable: acetate-based films and nitrocellulose-based films. Both these types of film give off odors (much like vinegar) when kept in airtight containers. The gasses associated with the odors cause other films to deteriorate. Nitrocellulose film is highly combustible as well, so it not only off gasses chemicals which will damage other materials stored nearby, it is a fire hazard. The safest program for a small archive holding either of these two types of films is to plan with a conservator to make prints and copy negatives, and then discard the originals.
The third generic type of film is safety film. Safety film is usually easily identified because in small letter on the edge of the negative will be printed "safety film." These films have chemically stable bases. The foundation for survival of images on safety film depends upon the processing of the film and the storage of it. By the time you receive film in the archives, the processing is finished. Apart from expensive conservation processes, you can only affect the films' survival by the storage conditions you provide.
Storage
The materials used in storing photographs make significant differences in the expected life of the images. There are a number of standards that help guarantee photographs are preserved. These are provided on the links page. Use reputable supplies when purchasing storage materials for photographs and negatives. Be especially concerned with plastic sleeves many off gas and can substantially damage prints and negatives if used for storage. Polypropylene, polyethylene, or archival polyester (commonly known as Mylar) are safe to use for photographic materials. All three pass the Photographic Activity Test (PAT); most other plastics do not pass the PAT, and you should not used.
The advantage of plastic sleeves is that the negative and prints can be seen easily without removing it from its sleeve, thus reducing chances of scratches to the emulsion surface or oils from human hands getting on the film. Disadvantages are an increased chance of mold growing on the emulsion because of high relative humidity. If the film is clean and dry when you store it in one of these three sleeves, it should remain safe as long as the environment in the storage box and the archives generally remains stable.
Photographic prints need a dark, cool, relatively dry environment. It is best, however, to store the prints in a different location from the negatives. By storing negatives and prints separately, materials of similar or identical size can be stored together so every item in the box mutually supports the other items. Also, by storing negatives in a separate location, you lessen the chance that an accident such as minor flood or localized fire, will destroy both positive and negative images.
You can choose to store prints in folders with interleaving acid free paper and then in standard document boxes. Also use sleeves or envelopes that are the same size as your prints or negatives. Do not try to force items into to small enclosures where they can be damaged or in to large enclosures as well. Select boxes that are made for the specific size of your prints or negatives and sleeves.
When you store prints in standard document boxes and acid free folders, limit the prints to about ten to fifteen prints per folder, interleaved with acid-free paper. This guarantees that the prints will not protrude outside the folder when it is scored at the bottom. If you are short on supplies you can store more per folder but be very careful when retrieving folders. You can store more than 10 prints per folder if they are smaller then 8 x10.
Storing color prints works much the same as black and white prints. The major difference is that color prints are much more susceptible to damage from light than black and white prints. And all photographic materials, indeed all archival materials, should be stored in dust-free and light free environment, which argues in favor of a totally enclosed storage system such as a box as opposed to some of the albums that many vendors sell.
A variety of companies offer storage materials used frequently within the archival community:
Light Impressions at www.lightimpressionsdirect.com
The Hollinger Corporation at www.hollingercorp.com
Metal Edge, Inc. at www.metaledgeinc.com
Arrangement of Photograph Collections
Negatives and prints should be identified by a common numbering system. This common numbering system will make easy finding both the negative of an image and any prints of an image in your collection. The identification number will have at least three parts: a collection tag or number, a series number or letter(s), and an individual image number. Begin the identifying number with the collection generally an accession number or some other unique identifier.
Just as with paper records, photograph collections may consist of different series. The series may be by topic: Pride Festivals; fund raising events; political action activities; annual meetings; etc. Another way the series may occur is chronologically with photographs grouped by year or years. Scrapbooks offer another series arrangement possibility. While this last seems chronological, it may have significant exceptions to a chronological order. After deciding what series exist within a collection, it may be most simple to assign a number or letter code to each series, rather than spell out the complete name of the series. A number or letter code allows your identification or call number assigned to a photograph to be shorter and simpler.
Once you have a clear understanding of the series within a collection, then you can begin assigning identifying numbers to the images within a series. To avoid a mess and later confusion, work only on one series at a time. Assign the same item number to both the negative of the image and all prints of that negative. As a help in doing this, create temporary enclosures out of acid-free paper folded to form makeshift envelopes. Write the identifying code (collection, series and item identification tags) on the paper. Eventually, you will separate the negatives from the prints; and at that time, you need to make certain that you have the identifying number written on the temporary enclosure of both negatives and prints.
Online photographic preservation resources:
• The Northeast Document Conservation Center http://www.nedcc.org/welcome/photo.htm
• The Minnesota Historical Society http://www.mnhs.org/preserve/conservation/photographs.html
• The Library of Congress http://www.loc.gov/preserv/care/photolea.html This site always provides a number of links to additional sources of information.
University of North Carolina http://www.lib.unc.edu/ncc/pha/pres.html
This threat is less than originally thought since polypropylene, polyethylene and archival polyester “breathe” allowing, over a period of time, the same relative humidity to exist inside the sleeve as exists outside it in the storage container.
Return to Information for Community Archives home page.
