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Copying and cold storage

Copying methods such as duplication and digitisation are an important element in any cellulose acetate preservation plan. Copying is an effective strategy for preserving the information contained on an item. In some cases, it is the information only that will need to be preserved. In these cases, copying alone is sufficient as a preservation strategy. In many cases, however, institutions will want to preserve originals after copying. In these cases, copying may be an effective strategy for providing access to the information. Fragile or deteriorated originals can then be stored at low or very low temperatures without the need for handling.

“Generally the preservation of acetate film collections will require an approach that combines the systematic duplication of acetate film materials onto polyester based film with the cool/cold storage of original film materials to extend the useable life. Often for small collections it will be most economical to duplicate the collections, while large acetate film collections will require a combined approach of cool/cold storage and a long term plan for preservation” (Puglia,1995, p.50)

McCormick-Goodhart advocates cold storage as being more economical:

“Despite the seemingly high construction and operating costs, the preservation benefit derived from the custom cold vault is enormous. A thorough economic comparison with copying or duplication strategies will reveal that copies actually cost more, suffer loss in quality, and fail to preserve the images in their original format.” (McCormick-Goodhart, 1999, p.20)

Henry Wilhelm makes a similar point:

“With large quantities of materials, it is much less expensive to preserve the original films than to make duplicates; in addition, cold storage allows preservation of the original artefact, and the subtle – or sometimes major – image quality losses that always occur when making duplicates are avoided” (Wilhelm, 1993, p. 692)

In order to determine the most cost effective strategy for any given collection, a cost-benefit analysis of cool storage as opposed to duplication should be carried out.

Both Puglia (1995) and Nishimura (1995) have provided guidelines for calculating the cost benefits of implementing different preservation strategies. It is important to note that in his calculations, Puglia assumes that polyester duplicates will not be placed in cold storage, and that they are likely to last 500 years. He also assumes that originals are not kept.

When copying, it is also important to factor in the costs of inspecting copies to ensure standards have been adhered to - which are often greater than the actual copying costs. Copying costs are also highly dependent on the format of the material to be copied.

Choice of copying strategies will necessarily depend on the use that will be made of the copy and the costs and risks associated with maintaining access to copies. For example, digitisation confers the ability to provide ready access and might be considered suitable for highly used items. However, methods of preserving access to digital materials are largely untried and might be considered unreliable.


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