General conservation techniques
Photographic collections should be stored in a cool, dry and stable environment. Our photographs are kept in conditioned stores, with air filtration and conditioning to the recommended levels of 16–18°C, 40–45% humidity. Preferably, research/study areas should be separated from storage areas, and lights in stores should be used only for removing/returning items.
All natural light should be excluded. Fluorescent lights, to provide background lighting, should be sleeved to block out ultra-violet light. Lights for detailed work should be switched locally, and concentrated on working surfaces only.
Storage and display
The general storage/display environment is the most important consideration in any photographic archive, and the most cost-effective investment. If this has not already been done, you should assess the existing environment with the help of monitoring instruments to provide a profile of diurnal and seasonal fluctuations, and then attempt to reduce these fluctuations to provide a stable, dry, cool storage environment. Obviously, with the compound nature of photographic artefacts, any storage standards are a compromise. You may be able to borrow or hire measuring instruments from your local Area Museums Service.
Because of the huge size and bulk of our collection, we use industrial units, which may not be appropriate for a smaller collection. With a conditioned store, we are able to use a variety of storage materials, but none is universally satisfactory in very damp or very dry conditions.
The general considerations are:
- Shelves and cabinets should be made of stainless steel or stove-enamelled metal. These should be robust and well able to bear the heavy loads of photographic materials. Consideration should be given to the risks of storing heavy materials on very high or very low shelves: the heaviest items should be stored at waist level.
- All storage and mounting materials should be made of 100% neutral polyester (tradenames: Mylar, Secol and Melanex) or of 100% rag un-buffered lignin-free and sulphur-free paper and board. Neutralised pulp boards and paper are not satisfactory over the long time span which should be envisaged for archival storage. These papers, boards and boxes are available from suppliers listed on the enclosed sheet.
- Any glues and adhesives should be starch or cellulose water-based adhesives, which are easily reversible. No sellotape, double-sided tape, dry-mounting tissue etc should be used.
- If foam is to be used as a lining for drawers and boxes, it must be Plastazote brand.
- Cotton gloves must be used at all times when handling photographic materials; working surfaces should be clean and dry, and should be covered with sheets of unbleached calico to soften the surface and cushion the material. Both gloves and sheets should be washed frequently, using a mild soap or neutral washing agent.
- 2B pencils should be used for any writing, and the print laid on a hard board before writing on the back, to minimise pressure on the emulsion.
Recommended display conditions for photographic materials
1. Eliminate all ultra violet light and reduce general light levels to 50 lux.
Fluorescent lights can be sleeved with UV filter tubing; daylight can be reduced with blinds or by placing UV protection film on window panes. Spotlights should not be located close to the cased objects.
2. Temperature and humidity should be stabilised at levels of approximately 18–20°c and 50% +/- 5%.
This is difficult to maintain in most display areas and even within cases. There are certain things which will help you to achieve this:
- Keep lights outside cases; keep light levels (and therefore heat levels) down; preferably use cool lighting (e.g. fluorescents, coolspots) rather than hot lighting (e.g. spotlights).
- Certain case and display materials will act as buffers in reducing changes in humidity if they are conditioned to the desired humidity in advance—particularly woods and textiles.
3. Use display materials—mounts, coverings, adhesives—which are relatively inert and do not release acid pollutants.
In general, the best rule for this is to avoid the use of any compound woods (e.g. blockboard, chipboard). Hardboard is generally a ‘safe’ wood to use.
Textiles with the minimum of treatments, i.e. unbleached, undyed materials, are useful. In particular, if you are displaying any material with silver components or silver-based emulsions you should avoid the use of felt; it is harmful to silver because of treatments applied to it during manufacture.
Using photograph albums
What type of album should I choose?
The albums which you purchase for your photographs should be strong board which is acid-free, and also unbuffered, lignin- and sulphur-free: these pollutants are commonly found in ‘archival’ products but are damaging to photographs.
An alternative to buying a ready-made album, which may not have these properties, is to make up an album with archival boards and with a post binding. The posts should be nylon: these can be purchased from printing and bookbinding suppliers.
The albums should have ‘spacers’ between pages at the binding if you are mounting any images which are already on cards—to avoid breaking the binding and/or putting pressure on the image.
Tissue paper which has the same properties as the board above should be used for interleaving.
The main problem with album presentation is mechanical. You must ensure that photographs are firmly attached to boards so that they do not move when the boards are turned, and that the photographs themselves are not in danger of being caught in the binding or damaged by handling.
Photographs should be mounted into the album with archival photo corners, of polyester or paper, or with hinges, rather than gluing the image over the whole surface.
The type of mount will depend on the weight and condition of the original: for example, a carte de visite portrait might be attached with corners, but a fragile and brittle albumen print without its own backing should be fixed with hinges.
Tissue for hinge mounting should be as described above for interleaving.
The glues used are wheat starch or methyl cellulose: you should not use standard wallpaper paste.
You should wear cotton gloves at all times while handling the photographs for sleeving or mounting, and work on a table covered with a clean cotton cloth. When the album is complete, it should be stored in a cool, dry and stable environment.
Photographic conservation: a bibliography
Susie Clarke, ‘Care of Photographic Moving Images and Sound Collections’, paper presented at the Institute of Paper Conservation Photo ’98 conference (York: Institute of Paper Conservation, 1998)
A. E. Fleming, ‘Conservation and Storage: Photographic Materials’, in John Thompson (ed.), Manual of Curatorship (London: Butterworth, 1984)
Klaus B. Hendricks, The preservation and restoration of photographic materials in archives and libraries: a RAMP study with guidelines, (Paris: UNESCO, 1984)
Laurence E. Keefe and Dennis Inch, The Life of a Photograph (London: Focal Press, 1984)
Bertrand Lavédrine, A Guide to the Preventive Conservation of Photographic Collections (Los Angeles, California: Getty Publications, 2003)
James Reilly, Care and Identification of Nineteenth Century Photographs (Rochester, New York: Eastman Kodak, 1986)
Siegfried Rempel, ‘The care of black and white photographic collections: cleaning and stabilisation’, Technical Bulletin—Canadian Conservation Institute, 9 (1980)
Siegfried Rempel, The Care of Photographs (New York, New York: Nick Lyons Books, 1987)
Mary Lynn Ritzenthaler, Gerald J. Munoff, and Margery S. Long. Archives and Manuscripts: Administration of Photographic Collections (Chicago, Illinois: Society of American Archivists, 1984)
M. Seaborne and S. Nuefeld, ‘Historic photograph collection and management at the Museum of London’, Museums Journal, 2 (1982)
Alice Swan, The Care and Conservation of Photographic Material (London: Crafts Council, 1981)
Robert A. Weinstein and Larry Booth, Collection, Use and Care of Historical Photographs (Nashville, Tennessee: American Association for State and Local History, 1977)
Standards covering the storage of photographic materials
BS 1153:1975 Recommendations for processing and storage of silver gelatin microfilm
BS 5454:1977 The storage and exhibition of archival documents section 12 pp 6-7
BS 5687:1979 Recommendations for storage conditions for silver image photographic plates for record purposes (revised 1985)
ISO 5466:1980 Photography: practice for the storage of processed safety photographic film (revised 1985)
ISO 6051:1980 Photography: silver image photographic paper prints for record purposes—storage conditions (revised 1985)