Metal Clays

Initial writing 12/7/23

Additions 12/8/23 – More to come (with any luck!)

Nancy LT Hamilton

Please see my Disclaimers page

There are so many types of metal clay these days (120 per the AMCAW –  I’m having trouble finding them all!).  A lot has changed since I first discovered the media at the end of the nineties!

    Beauty. (Metal clay type – PMC3 and Aura 22 Gold), sterling, pearls, sapphires, blue diamonds.

I was certified by the PMC Guild (January 2005) in a class with CeCe Wire, run through Rio Grande.  My work was chosen to be in the invitational shows at Purdue. My images (a few are horrible!) can be found in three volumes of the PMC Annuals: volumes 2, 3, and 4.  You can also check out my Gallery on Pinterest. You can find volumes 1 -5 of the PMC Annuals on eBay and other sites. I miss Studio PMC, as well as Art Jewelry Magazine!  They were great.  But hey, did you know you can find back issues of Studio PMC at Rio Grande?  They are full of inspiration and techniques even though they are over 20 years old. I published an article you can still read in Studio PMC:  Beautiful Backs, Fall 2005, Volume 8 Number 3.

Contents

Metal Clay – a Brief Description

Metal clay comes in gold, silver, fine silver, Argentium silver, steel, brass, bronze, and copper – with various formulas – depending on the manufacturer.

Very briefly,  Metal clay is a powdered metal mixed with water and a binder, resulting in clay that can be stamped, carved, drilled, bent, joined, twisted, rolled, etc.  The clay is either torch-fired (only works for specific brands, sizes of work, and types – check your instructions) or placed into a kiln.

When placed into a kiln, the metal sinters – the atoms join together, forming a pretty solid metal.  I say “pretty solid” because there are air pockets present. The fewer air pockets there are, the stronger the metal.  By optimally firing the clay, you can form a more complete bond between the atoms of silver and copper.  In general, though, Metal clay tends to be more porous than sheet metal. The finer the silver particles, the lower the temperature required for sintering.

When optimally heated, the water and binder are burned out, moving the atoms closer together.  An optimal firing temperature will fuse the atoms but stop short of full fusion, which is also known as melting.  This is the reason that fired clay is more porous than sheet metal.

  Minimally fired silver clay under a microscope.

  Image from AMCAW Understanding Sintering in Metal Clay.

Image one shows dry clay, the second shows less than optimal firing, and the third shows optimally fired clay.

To ensure that your metal is completely sintered, it is recommended that you fire it at the highest recommended temperature for the longest recommended time.

Firing Types and Methods

Fine silver and 22k gold clays can be fired on an open shelf in a kiln.  This is due to the lack of copper in the metal.  At temperatures from 879°C (1598°F) to 980°C (1796°F), copper reacts with ambient oxygen to form copper oxides.  These oxides prevent the atoms of your metal from fusing.  This is why you can heat fine silver and 22k gold (very low copper content) without charcoal in an open kiln – there’s no copper to form oxides.

Base metals and steel need a two-stage firing – the first stage burns off the binder and any remaining moisture.  The second stage fuses the metal.  The clay is buried in carbon, which reduces the amount of oxygen that can interact with the copper.  Without oxidation occurring, the metal molecules can fuse together.

A torch flame eats any oxygen that is in its path – for a short period of time.  This fact allows us to fire small pieces of pure copper and some bronzes with a torch.  I have also had success fusing 22k and 24k gold slip to my work because of the oxygen-gobbling nature of a torch flame.  Again, the amount of time firing and the size of the work is limited.  See my video on torch-firing gold on copper-based metals.

History

I will lead you off-site (be sure to come back!) to read what others have written, as my main concerns on this page are the processes, tips, and tricks.

Developers of Metal Clay in Order of Their Appearance in the World

  • Aida Chemical Industries.  Art Clay brand.  They received their patent in 1991.
  • Mitsubishi Materials Corporation.  PMC brand.  They stopped manufacturing the clay in March 2023.  Received their patent on July 12, 1994.
  • Hadar Jacobson.  Hadar’s Clay brand. (Initial experiments 2004)
  • Dr. Bill Struve.  Metal Adventures brand.  Bill invented the method for filing copper and bronze clays in a carbon.  (Launched 2008). He invented Silver EZ960  (sterling) and FS999, Sold by Cool Tools  (launched in 2016).  It appears that Metal Adventures shut down in 2022.  Their website is no longer active, and I couldn’t find any information on Dr. Bill Struve PhD.
  • Prometheus.  (Launched 2009).  Country of Origin – Turkey.
  • Aussie Metal Clays (Launched 10/3/2019)  Country of Origin – Australia.  1st Argentium metal clay.
  • Phoenix Torch Fireable Metal Clay created by Cool Tools.  (Launched Spring of 2023).
  • Clay Revolution – Project X clays.  (Launched June 2023).
  • Cool Tools. Art Clay Gold and Art Clay Copper brands. (Unknown launch date).
  • Five Star Clays – (Unknown launch date).
  • FYI Metal Clay – (Unknown launch date).
  • Goldie – (Unknown launch date). Country of Origin – Poland.
  • Metal Magic – (Unknown launch date). Not sure if they are still in business.
  • Aureus Bright Bronze Clay and Cyprus Copper Clay (developed by Cindy Silas) (Unknown launch date) Country of origin – USA. Not sure if they are still in business.
  • Meteor Silver – (Unknown launch date).  Country of origin – France. Not sure if they are still in business.
  • Zabs Clay.  Country of origin – France
  • Metal Mania Metal Clay. I am not sure if they are still in business.

Helpful Tools

AMCAW Metal Clay Firing Methods and Equipment

Art Clay World USA – Sizing Recommendations for Art Clay (.999% Fine) Silver Rings

Art Jewelry Forum

Cool Tools Firing Guide and Information

Gemstone Firing Guide by Cool Tools – Fire natural and synthetic stones – which works and which doesn’t

 Research and Resources

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