Early phenol-formaldehyde and urea-formaldehyde plastics

James Tapley <jthandbook [at] aol__com> writes

>I have acquired a badly damaged (cracks, losses) art deco Reliure
>Jotau industrial molded "Bakelite" bookbinding. While these bindings
>are always referred to as made of Bakelite I believe, based on the
>unpainted but rather colorful plastic, that they are perhaps made of
>a urea-formaldehyde  plastic. Can anyone suggest a relatively simple
>and non-destructive test for distinguishing between urea- and
>phenol-formaldehyde plastics? ...

It sounds like you have a urea-formaldehyde plastic of the "Beetle"
variety. That molding powder came on the market in 1928, so the date
is another way to tell what you might have.  Phenol-formaldehydes
came out in 1909. You'd need a fairly well-equipped conservation lab
to do the spot tests, as they require concentrated acids and other
toxic reagents.  The tests are destructive to the sample, but you
can use a small piece that has detached or abraded powder from an
unobtrusive area, so they are relatively non-destructive to the
object.  The best references for the tests are

    Dietrich Braun.
    Identification of Plastics.
    Macmillan Publishing, Co,Inc., NY, 1982, pg. 77

and

    K.J. Saunders.
    The Identification of Plastics and Rubbers.
    Chapman and Hall, Ltd., 1966, pg. 35.

A good recent reference on the conservation of plastics is

    Anita Quye and Colin Williamson, ed.
    Plastics: Collecting and Conserving.
    NMS Publishing, Ltd., Scotland, 1999.

Also see

    Sharon Blank
    "An Introduction to plastics and rubbers in collections"
    Studies in Conservation, Volume 35, Number 2, May 1990.

Paul Storch
Senior Objects Conservator
Daniels Objects Conservation Laboratory (DOCL)
B-109.1, Minnesota History Center
345 Kellogg Blvd. West
St. Paul, MN  55102-1906
651-297-5774
Fax: 651-297-2967


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                  Conservation DistList Instance 18:34
                 Distributed: Tuesday, January 25, 2005
                       Message Id: cdl-18-34-005
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