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Subject: Discarding acetate microfilm masters

Discarding acetate microfilm masters

From: George Brock-Nannestad <pattac>
Date: Sunday, September 24, 2006
Jennifer Lloyd <jlloyd [at] nla__gov__au> writes

>We have commenced a project to create new polyester microfilm
>masters of collections for which we hold prime preservation
>responsibility (we own the master). The new polyester master is
>created via direct contact copying from the original acetate camera
>master. It is not possible to refilm these collections. This means
>that the new polyester master is a second-generation film. The issue
>I am grappling with is this: Should we discard the original
>cellulose acetate camera master?

Sadly, it seems the time has come to digitize. Sadly, because it is
a farewell to a well-proven technology that unfortunately relied on
a non-stable support. In view of that I shall try to give my views
to the issues. However, let me first state that I regard a microform
(particularly fiche formats) as very user friendly.

>    *   is it a problem to have only a second-generation master if
>        the first-generation is discarded?

In the analogue world it is a master with less resolution and more
need for the ominous stamp "best available copy".

>    *   how can I be confident that the new polyester master is as
>        good a copy as can be achieved?

By running tests, using resolution test charts--measuring Modulation
Transfer Function (specialists for that) if relevant.

>    *   justifying the resources needed for ongoing monitoring of
>        vinegar syndrome

At least budget for this, in order to see how much money might be
made available for alternative solutions.

>    *   rationale for keeping acetate masters when we know they will
>        eventually disintegrate from vinegar syndrome

Only if the future promises better "as good a copy as can be
achieved" before they have disintegrated. It is not likely, though.

>    *   rationale for discarding the acetate masters when they are
>        the closest thing to the original that we have
>Any thoughts you may have would be appreciated,

The rationale would be trust in the alternative solution.

The digitizing should be to a standard that a re-creation of a
microform from a digitized file will be indistinguishable from using
the master in a microfilm reader/printer. All of this may be
determined objectively, but obviously this is a complete project,
needing special funding. However, the savings on storing and copying
the analog material will be huge.

This way you create a digital surrogate that will perform precisely
as the master microforms you have now, and the computer output
microfilm will be the use copies, identical to the analog master you
have discarded. This will be a better image than a contact diazo use
copy obtained from a secondary master. You will be bound to a
digital store, but procedures are already in place for maintaining
it in the long term.

It will be interesting to learn how you proceed.

George Brock-Nannestad

                  Conservation DistList Instance 20:17
               Distributed: Thursday, September 28, 2006
                       Message Id: cdl-20-17-004
Received on Sunday, 24 September, 2006

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