Steel and vinyl phonograph records

> A friend from a famous music museum in Rio asks for assistance in
> locating resources for conserving their steel and vinyl phonograph
> record collection. It's under HVAC controls but the record surfaces
> are separating and disintegrating from age. Thanks.

The discs your friend is referring to are acetate discs.  The following
excerpt was lifted from an article I wrote about the care and handling
of sound recordings.


    **** Moderator's comments:   The complete article is available in
    Conservation OnLine
    (Browse by Organization/
       Commission on Preservation and Access/
         Reports)

    [...]
    The lifespan of a plastic is largely determined at the manufacturing
    stage. Variables such as basic resin, the materials added to the
    basic resin to alter its properties, the lamination of materials
    with dissimilar properties, and the manufacturing process itself,
    all directly affect the lifespan of the plastic.   Post-manufacture
    environmental factors such as storage conditions, temperature,
    humidity, and handling also contribute to the long-term stability of
    the plastics.

    Acetate Discs
    Prior to the advent of magnetic tape, instantaneous recordings were
    made chiefly on acetate discs.  The chemical makeup of these discs,
    therefore, had to be a compromise between ease of engraving and the
    quality of the recording that resulted.

    Since the 1930s, most blank acetate discs have been manufactured
    with a base, usually aluminum (although glass was used during the
    war years and cardboard for inexpensive home recordings), that was
    coated with nitrocellulose lacquer plasticized with castor oil.
    Because of the lacquer's inherent properties, acetate discs are the
    least stable type of sound recording.

    Continuous shrinkage of the lacquer coating due to the loss of the
    castor oil plasticizer is the primary destructive force.  The
    gradual loss of plasticizer causes progressive embrittlement and the
    irreversible loss of sound information.  Because the coating is
    bonded to a core which cannot shrink, internal stresses result,
    which in turn cause cracking and peeling of the coating.

    Nitrocellulose acetate decomposes continuously and over time reacts
    with water vapour or oxygen to produce acids that act as a catalyst
    for several other chemical reactions such as the release of palmitic
    acid, a white waxy substance.  As with most chemical reactions,
    these reactions are accelerated with elevated temperature and
    humidity levels.
    [...]

Because acetate discs are unstable, a systematic copying program should
be put in place preferably before the advent of catastrophic failure
(ie. the flaking and detaching of the acetate coating).  In a few cases
the acetate can be re-attached.   Unfortunately, the degradation itself
is irreversible. You will need to transfer the information onto a more
stable medium (reel-to-reel tape and if you like a digital back-up)
immediately. You will need to find an audio conservator. If you cannot,
then a recording studio capable of playing 78s properly must be found,
i.e. a studio equipped with: record cleaning equipment with an operator
trained and experienced in cleaning fragile discs, a turntable which can
play 78s, a 12" tonearm (if you have 16" records), preamplifier with
varying playback equalization (bypassing RIAA playback EQ), a large
range of styli of various sizes and shapes and an audio engineer who is
sensitive to the era's recording techniques, technology and sound.  The
latter is particularly important if the machine on which the recording
was made is not known; the setting of the playback EQ must be done by
ear.  If an experienced audio engineer cannot be found, a dub can be
made with no playback EQ whatsoever until an experienced conservator can
be found to do the work.  Even if your records are mono, make sure that
the work is done in stereo, as quite often there will be subtle, and
sometimes not so subtle, differences between the two sides of the
groove.

Peruse the ARSC (Association for Recorded Sound Collections) Membership
Directory for names of people who might be able to do the work.  The
ARSC Membership Directory should be available on Interlibrary loan.

Also, an interesting technological innovation to deal with the problem
of playing cracking and peeling acetate discs comes from the Swiss
National Sound Archive.  They, in co-operation with the Ecole
Polytechnique Federale de Lausanne, have devised a "Fibre Optic Reader"
which uses a fibre optic cable to replace the traditional stylus and
tonearm combination.  The fibre optic cable sits in the groove and in
conjunction with a laser beam is capable of reading groove information.
The light weight of the fibre optic allows a damaged record to be played
without further damaging the disc.  I have not worked with the device
and do not know how good the audio quality or tracking ability are.

For more information contact:

    Fonoteca Nazionale Svizzera
    Via Foce 1
    6900 Lugano
    Tel: 44 91 52 65 96
    Fax: 41 91 52 61 69

Gilles St-Laurent
National Library of Canada

                                  ***
                  Conservation DistList Instance 8:19
               Distributed: Wednesday, September 14, 1994
                        Message Id: cdl-8-19-003
                                  ***