Transcription discs

Andrea Bowes <abowes [at] compusmart__ab__ca> writes

>The archives that I work with has several large collections of glass
>transcription discs from the 40's and 50's and they will be
>reformatting a selection of them soon.  I am unfamiliar with this
>archival record format and would like some further information
>before we proceed with this project.  In particular several discs
>have a white crystal formation over their surface.  What is the
>black layer of the disc made of?  What might the crystals be?
>Finally is there a safe way to remove them?

There's a fair amount of literature on transcription discs, some of
which discusses what they're made of and how they age.  The answers
to the question of how to clean them are many and varied, and tend
to be controversial; there is no single authoritative answer.  It is
generally agreed, however, that the crystals on the surface are best
left alone until it is time to reformat.  The coating on the discs
is generally reported as being nitrocellulose (some sources report
cellulose acetate. Our work at GSU confirmed published reports that
the white substance is composed of fatty acids, primarily palmitic
acid and stearic acid, which are produced as the plasticizers in the
disc coating deteriorate.

A classic source for information on these discs  is "Preservation
and Storage of Sound Recordings, by A.G. Pickett and M.M. Lemcoe,
1959 (republished by the Association for Recorded Sound Collections
in the early 1990s).  Pickett and Lemcoe discuss what these discs
are made of and how they behaved under accelerated aging, but were
not in a position at that time to know how the discs would appear
following nearly 30 additional years of routine storage.

Other sources of information include:

    Gerald Gibson, "Decay and Degradation of Disk and Cylinder
    Recordings in Storage," in Archiving the Audio-Visual Heritage
    (1988, ed. by Orbanz) (pp. 47 - 54).

    A Manual of Sound Archive Administration, by Alan Ward (1990).

    "The Care and Handling of Recorded Sound Materials" by Gilles
    St.-Laurent. Originally published by the Commission on
    Preservation and Access, 1991, it was republished in the ARSC
    Journal, 23:2 (fall 1992): 144 - 156.

Finally, in 1997, my colleagues and I at Georgia State University
published "A Review and Discussion of Selected Acetate Disc Cleaning
Methods: Anecdotal, Experiential and Investigative Findings," ARSC
Journal 28:1, (Spring 1997):  1 - 23.  The piece includes discussion
of the physical properties of the coating on these discs, plus
several common cleaning methods.

There's a good bit more literature out there, but these are the ones
that come immediately to mind this morning.  I hope this helps.

Chris Paton
Archivist, Popular Music Collection
Special Collections Department
Pullen Library
Georgia State University

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                  Conservation DistList Instance 12:49
                Distributed: Wednesday, December 2, 1998
                       Message Id: cdl-12-49-002
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