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Copying and cold storage
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.
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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:
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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:
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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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