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Photographic Preservation Workshops, May 2002
Report by Cynthia Ball, Conservator, Jasper Alberta
Last May, I attended 2 of the 3 workshops presented prior to the ACA Conference in Vancouver. The first workshop, on low cost cold storage solutions for photographic media, was presented by Rosaleen Hill, Conservator for the BC Archival Preservation Service.
Cold storage is recognized as the primary preservation solution for colour photographic media and deteriorating cellulose nitrate and cellulose acetate negatives. There will be loss of these original images if they are stored at room temperature and a relative humidity of 40 to 55 per cent. Glass plates should not be placed in cold storage. The type of cold storage system chosen will depend on the size of the collection requiring cold storage, the cost of the system and the funds available, the amount of time collections are required to be out of cold storage and how access is provided to the images. There are 3 types of cold storage units available, including a custom engineered walk-in cold vault (in place at the National Archives of Canada and the Provincial Archives of Manitoba), a walk-in or restaurant type of freezer (in place at the City of Vancouver Archives) and an upright frost-free household freezer. If an institution requires more than 15 upright frost-free freezers for storage of their colour photographic materials or their cellulose nitrate or acetate negatives, it is more economical to install a walk-in or restaurant type of freezer. It is also important to consider where such freezers are placed because they can generate sufficient heat in a room to cause problems with air conditioners or heating, ventilation and air conditioning systems
The relative humidity is controlled in a custom engineered walk-in cold vault, so special packing methods are not needed. However, because the relative humidity is not controlled in a walk-in or restaurant type of freezer or in a household freezer, the photographic records stored there must be packed in a series of Ziploc bags with dried acid-free mat board and humidity indicator cards. This packing method is called the Critical Moisture Indicator Method and was developed by Mark McCormick-Goodhart while working at the Smithsonian Institution. Freezer packing kits can be developed in-house or are available commercially from Metal Edge Inc., 6340 Bandini Blvd., Commerce, CA 90040, telephone: 1-800-862-2228, website www.metaledgeinc.com.
Additional information is available about the Critical Moisture Indicator Method from "Methods for Creating Cold Storage Environments" / McCormick-Goodhart, Mark H., 1999, in Care of Photographic Moving Image & Sound Collections, ed. Susie Clark, p.19-25. Leigh Lodge: Institute of Paper Conservation.
The significant benefits of placing colour photographic materials and deteriorating cellulose nitrate and acetate negatives in cold storage were discussed during the workshop. Cold storage will increase the lifespan of these collections by decreasing the rate of chemical deterioration. This will buy time to implement a reformatting program, whether it be the production of digitized scans or traditional copy negatives. Digitization is not preservation, but can provide increased access to collections, while cold storage preserves the originals.
The Image Permanence Institute has produced several useful tools that can help to determine the condition of and potential usefulness of collections stored at certain environments. These include the Acetate Film Wheel (available for loan from Michael Gourlie, ASA Advisor), the Colour Photographic Materials Wheel, A-D strips and the Preservation Calculator, which can be downloaded free of charge from their website: www.rit.edu/ipi/.
The second workshop I attended was a case study about the digitization of photographic holdings presented by Ann Carroll, Archivist and Sue Bigelow, Conservator at the City of Vancouver Archives. The City of Vancouver Archives has been scanning photo-graphic images in their holdings to decrease handling of certain images, such as deteriorating glass plate negatives, and to provide increased access to images using their website. They have developed a personal computer based system that creates a high resolution master file for saleable copies and a low resolution web image using only 1 scan of the original image. The software in use is DB Textworks for Windows by Inmagic Inc. If a negative is in good condition it, rather than the print, is usually scanned because it can generally provide a more detailed version of the image. Interestingly, nitrate negatives in poor condition often provide a clearer image when scanned than some darkroom prints made years ago.
Scans are done at 12 bits and then converted to 8 bits immediately. A density range of at least 3.0 is preferred with a dynamic maximum of 3.2. Images are scanned at a resolution of 600 pixels per inch, providing adequate detail to produce an 8 x 10" or a 30 x 40" print, without having to remove the original negative from cold storage. Master files are stored in a Tag Image File Format (TIF), while web files are in JPEG format. The scanned images are sent directly to another computer which creates 2 compact disks of the images. One of the disks is stored at the Archives, while the second copy is stored off-site.
To date, the City of Vancouver Archives has scanned 25,000 images. Only photographs in the public domain are currently being scanned. It is evident that there are many questions to be answered when setting up a scanning program. It was interesting to learn how City of Vancouver Archives' staff answered these questions, what decisions are working for them and things that they would change given the opportunity. The digitization program is successfully providing access to images in the holdings, while preservation measures are in place to care for the originals.
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