There are two brands of metal clay available today; Precious Metal
Clay and Art Clay Silver. There are a lot of similarities between
the two, and some differences. My experience is with Precious Metal
Clay (PMC), so the techniques and methods that I write about will be
from this vantage point.
When I began working with PMC in 1999 very little was
available about it. Consequently, I have developed my own style,
methods, and techniques, which I will share with you, hopefully as a
springboard for you to experiment with, and possibly incorporate in
your own way, into your work.
PMC, which actually is malleable fine silver and 24K gold, is a
revolutionary development in the precious metal industry. It is so
new that, while great strides have already been made in working with
it, it is a medium that is still in its infancy. Much of it's
potential is yet to be developed. As with any art form, the more
people who experience it, the more the diversity in tools,
techniques, etc., will transpire. Hopefully, these, too, will be
shared and will inspire more artists to take up the challenge (and
fun) of experiencing a new way of handling the ages old metals of
silver and gold.
Following are some excerpts from my workbook, 'Creating with
Precious Metal Clay'.
PMC is a revolutionary development in the precious metal industry.
It allows for easy creation of detail in designs that would be very
difficult and painstaking to achieve using conventional forms of
metal and methods of working. Expensive tools and equipment are not
needed to work with PMC.
It is a very versatile product. The silver and gold PMC can be used
separately, or in combination with each other, as in two-tone
pieces. PMC can be combined, before firing, with other materials
such as potter's clay, sterling silver, high-fired ceramics,
synthetic corundum stones, and, after firing, using epoxy, or
soldering methods. It can be enameled, carved, or even
wheel-thrown. Three dimensional pieces and hollow forms such as
beads and vases can easily be made.
PMC is a very 'forgiving' medium. Changes in the piece can be made
at any stage of creation, allowing for the design to truly evolve.
New designs can be tested with very little time commitment. You
will also learn that, with a little vigilance, there is virtually no
wasted PMC. Slightly or completely dried PMC can be re-hydrated to
working consistency, or made into slip (a paste form of PMC used for
joining and repairing).
PMC has incredible potential and limitless possibilities. Your
designs can be as simple or as intricate as you desire. As you
learn about PMC, your imagination will be more than sparked. You
will find yourself thinking of more design ideas than you have time
to create. By all means try new things and experiment with new
ideas. This is a product that is in its infancy. It has tremendous
potential and is very easily individualized. Experienced artisans,
jewelers, clay workers, bead-makers, etc., will find ways to
incorporate PMC into existing methods of working. Novice hobbyists
and budding artisans will have wonderful success from the very
beginning. You will find great satisfaction and encouragement when
you see the professional results you can achieve. Those who
experiences PMC will add a dimension to their work that has been
unavailable until now.
Properties of Standard PMC, PMC+, and PMC 3
Precious Metal Clay is available in pure silver, and in 24 Karat
There are three types of silver PMC-standard PMC, PMC+ (called PMC
Plus), and PMC 3. Each can be worked the same, using the same
tools, yet each type also has its own properties and
characteristics. These varying qualities are what make using PMC so
very versatile. Although each type of silver PMC has its own rate
of shrinkage, the shrinkage is uniform throughout the piece.
Therefore, the proportion and scale within the piece before it is
fired, will remain the same after firing, the piece will just be
smaller. Also note that the shrinkage will occur in all
directions-length, width, and thickness. One of the beauties of the
shrinkage characteristic is that you create the piece in a larger
size (definitely a plus for those of us who wear glasses), and the
detail becomes more enhanced after it has been fired.
In standard PMC, whether silver or gold, the binder is about 30% of
the content of the silver clay mixture. Since the binder burns
away, the piece will be about 70% of the original size after firing.
There is a PMC ruler made specifically to help measure the
shrinkage of standard PMC. I have found it to be very accurate.
THIS RULER WORKS FOR STANDARD PMC ONLY, BOTH SILVER AND GOLD. Each
side has a true 6" ruler. On one side there is also an expanded
ruler that shows the size the piece should be made before firing in
order to achieve the intended finished size. For example, if you
want a piece to be 1" long when it is finished, then you would use
the expanded ruler and actually make the piece the expanded 1". On
the reverse side there is a shrunken ruler. If you are using a
mold, for instance, that the size has already been determined, then
you would measure that mold with the true 6" ruler and check the
shrunken ruler to see what the actual after firing size would be.
So, a piece made from a 1" mold before firing would actually end up
being =BE" after it is fired.
Standard silver PMC is fired at 1650F for two hours. Gold is fired
at 1830F for two hours. After firing, PMC is stronger than the same
item made in conventional metal of the same purity. PMC is more
porous, therefore resulting in pieces that are lighter in weight
than their counterparts in conventional fine silver and 24K gold.
This characteristic is particularly advantageous when making larger
wearable art items.
Silver PMC+ has approximately 12% binder in the content of the clay,
and therefore shrinks to about 88% of its original size. It is
denser after firing than standard PMC, therefore is slightly
heavier. There are three firing temperature and time options for
PMC+. It only needs to be fired for 10 minutes, but can be fired
longer. When fired for two hours, at 1650F, it becomes almost as
strong as sterling silver. (See chapter about Firing). Firing at
the lower temperature of 1470F makes it possible to embed sterling
silver findings, such as earring posts, before firing.
Silver PMC 3 has the same shrinkage rate as PMC+. PMC 3 can also be
fired for as little as 10 minutes, or as long as two hours. If
fired for two hours it will become slightly denser than the other
two forms of PMC, and, therefore, slightly stronger. If fired for
two hours, PMC 3 must first be heated to about 250C for at least 10
minutes to be sure the binder burns away. The following two
photographs compare the shrinkage of the three types of PMC.
No matter which form of PMC you use, after firing it is pure
precious metal and can be handled as such. It can be sanded,
soldered, polished, tumbled, burnished, oxidized, wire brushed for a
satin finish, enameled, etc.