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The earliest plastic materials were natural organic substances such
as ivory, tortoiseshell, horn, bone, pearl and amber which could be
moulded and shaped.
The first man made plastic materials had been appearing from about
1850 onward. Pyroxilin (or xylonite) based on cellulose, camphor, and
nitric and sulphuric acids was first sold as Parkesine, and later the
more refined Celluloid was developed. A second type of plastic was
synthesised in the late nineteenth century based on formaldehyde added
to a protein derived from soured milk and known as casein.
However the most successful early synthetic plastic was Bakelite
which was developed early in the twentieth century. Based on a mixture
of formaldehyde and phenolic acid which forms a viscous liquid when
mixed and which sets permanently when heated into a hard material that
cannot be softened or dissolved. This is called a thermosetting
plastic which, once cast, can be further worked only by physical
processes such as cutting, filing, drilling and polishing.
Celluloid and casein jewellery was produced on a small scale,
encouraged by a fashion for heavy bracelets after the first world war
and into the 1920's. It took some years until Bakelite was refined and
colourful dyes were developed, but once this happened, Bakelite
jewellery was produced in greater volume from the late twenties
onwards. However the jewellery was still hand-crafted and production
was therefore limited, and as some materials were not stable over long
periods, jewellery in all three early materials has become scarce and
eagerly collectable.
The Bakelite Jewelry Book by Corinne Davidov and Ginny Redington
Dawes, Abbeville Press N.Y. 1988 ISBN 0-89659-867-5 has some excellent
pictures and information.
During the second world war, Bakelite production was channelled
exclusively towards the war effort, and by the end of the war, other
materials had been discovered.
Thermoplastics in the form of acrylic, polyester, polyamide,
polythene and PVC were developed whose physical properties were more
advanced than Bakelite. Thermoplastics can be shaped by heating and
never set permanently hard like the earlier thermosetting plastics.
Several of these have been used for jewellery and the most popular are
acrylic and polyester.
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