Dear Dr. Aspler,
I read with interest a recent message about Art Clay, a product
similar to Precious Metal Clay (PMC) that was developled in Japan
and has been the subject of a patent suit there for several years.
In response to the questions I’ve received, I’d like to pass along
what I know so far.
The material is a lot like PMC with some qualifications. For one
thing, I found it stickier and consequently less appealing to
handle than precious metal clay.
The firing is a little fussier, at least as described in the
paper that came packaged in the material I bought from Swest.
Basically they advise to dry the pieces overnight, then bring to
800 degrees C over the course of an hour and hold at that temp. for
30 minutes. This is not significantly different than the
recommended process for firing PMC (900 degrees C for two hours.) I
have heard mention of a firing time of ten minutes. This is not
described anywhere in the printed material that came with Art
Clay. It is possible to fire PMC for 10 minutes too. The result
looks like metal and can be polished, but it is so weak it can be
broken in the fingers. This is so obviously unacceptable that we
don’t mention it in the literature.
Shrinkage of Art Clay is less, but so is density. I sent a
sample to the lab in Japan and they confirmed that it is about 5%
less dense. That is, where PMC is 80% as dense as rolled metal, Art
Clay is 75% as dense.
Art Clay costs about 20-30% more than PMC. It shrinks less, but
not enough to offset this higher cost. Or to say it another way, a
dollar of PMC will make a bigger piece than a dollar of Art Clay.
I was disappointed with the printed material I got from Swest;
obviously a piece translated in Japan. I don’t think their support
approaches the combined efforts of Rio Grande and Mitsubishi as
shown in a video, web site, newsletter, Masters Classes, research
support and teaching support.
Because the matter is under litigation, Mitsubishi’s position will
be to watch with interest but take no aggressive action.
Thanks for keeping me informed,