Learn how to make your own 'metal clay' using powdered copper and organic binders. 

The first precious metal clays were introduced in the 1990's - made from pure silver powder and organic binders (Mitsubishi Materials Corp. makes PMC = Precious Metal Clay and Aida Chemical Industries makes Art Clay).  The silver clay behaved kind of like a ceramic clay, could be molded, sculpted, carved, extruded etc.  The metal clay was then 'fired' in a kiln or by torch, to produce a pure metal item.

Fine silver (.999 pure silver) is a noble metal, meaning that it resists oxidation and corrosion.  Many noble metals are also precious metal, gold, silver, platinum.  Because it resists oxidation, fine silver can be fused by heat in an oxygen (normal atmosphere) environment such as in a kiln or open torch flame.  When particles are heated, close to melting temperature, but not melting, they move close together and become sticky, adhereing to each other.  This compaction and partial fusing is called 'sintering'.  Sintering produces metals that are more porous and lighter than cast metal, also not as strong.  Gold clay later became available, but required higher firing temperatures and was very costly.
Precious metals are costly, and in recent years have grown even more expensive.  Many people worked on trying to make 'base metal' clays.  Base metals, such as copper, bronze (copper and tin) and brass (copper and zinc) do oxidize and corrode.  When heated in an oxygen atmosphere, base metal particles oxidize and do not stick together (sinter).  Industrially, metal powders are sintered in special kilns filled with inert gases.  This is virtually impossible to do in a home or small studio setting.  The inventor of BRONZClay (tm) and COPPRClay (tm), Bill Struve, found a wonderful way to fire base metals in a home kiln.  He used activated charcoal  in a closed, stainless steel container to produce a low oxygen environment for sintering base metal clay.  When heated to high temperatures, the charcoal tries to burn and uses any available oxygen in the area, thus preventing (and even reversing) oxidation of metal particles.

Step 1: Copper clay recipe

The basic recipe is organic binders, atomized metal (-325 mesh or smaller), glycerin and water.  Wear a fine particulate mask when handling dry powders, preferable N95 - no excuse not to BE SAFE and use safety equipment.  (Photo shows bronze powder:  I took this photo after I made the clay and grabbed the wrong bottle) 

1/2 tsp. corn starch
1/4 tsp. powdered xanthan gum (do not breathe in the powder!  It forms a VERY gummy slime when mixed with water)
glycerin - a few drops adds a little flexibility
3+  Tbsp atomized pure copper*
distilled water in a small spray bottle.
Wear your mask and carefully mix dry ingredients until you have a uniform mix.  No clumps of cornstarch visible.
Spray surface with some distilled water and carefully stir.  Add more spritzes of water and keep stirring until the mix starts to clump together.  Mix well between spritzes until your mixture starts to feel clay-like.  Lightly oil your hands with olive oil or natural hand balm and squeeze mixture.  If it holds together then you can knead by hand.  If mixture starts to crumble, work in a little more water.  If it is very sticky, let it dry a bit and rework, or add a little more metal powder or cornstarch.   Copper clay will have a reddish tine, shown in the second picture.
Set clay aside in a sealed container or plastic bag. 
Let clay rest for a while and go make your trilobite mold in step two.

   * Smallest metal particles are best, but it is hard to get finer than -325 mesh, about 44 microns.  Really good if you can find 1-20 micron powder, but it is expensive reagent grade copper.  Atomized metal is sold for use with plastic resins to 'cold cast' metal art objects.  Check art suppliers, Douglas and Sturgess, or TAP plastics.
Somebody sells powdered silver with a binder for DIY silver clay - I think it doesn't handle as well as PMC or Art clay silver. I forgot the name, but it's listed on the metalclayacademy website, under make your own metal clay.<br>Aluminum metal clay sounds difficult: aluminum oxidizes so quickly...
<p>I want to know how can i make copper/bronze clay....please guide me please !</p><p>nguyenanhtuan9989@gmail.com From Vietnam</p><p>Thanks alot</p>
This made my day, thanks for posting this! About how much shrinkage do you think you get after firing?
Very cool. You did a great job! :)
Its a shame there aren't programs here that would teach people how to do that. Much of the glass that ends up in landfills could be used.
Very, very cool instructable. Thank you. I don't know if I will ever use the concept but I am very pleased to know how it can be done. It reminds me of an article I read years ago about casting glass. Similar to lost wax casting, they mixed fine glass pieces with a binding agent ( I believe they used Elmers glue.) and formed the mixture into the shape they wished to cast. Either with a mold or hand formed. Once the material had dried sufficiently they then used a casting medium ( investment akin to plaster of paris but able to take much greater heat) and put the piece in a cask then poured the investment into the cast. After the investment had dried they then put it in a kiln and ran the temp up to a point where the glass would fuse. The binder burned off in the kiln leaving a fused model in the investment. Then came the cool down process. Glass must be cooled slowly or it will break. I believe the cool down process took days. I think Lalique made some glass items by a true lost wax process. <br> <br>
Thanks. I've played a little with homemade 'glass clay' - glass powder held together with an organic binder. I did not fire it in a mold - just on a kiln-washed shelf. I believe that there is a history of recycled, powdered glass beads made in Ghana... crushed glass powder mixed with colorants and packed into kaolin-coated clay molds and fired in wood-burning kilns. I think skilled artisans use the color of the kiln walls to estimate firing temperatures.
Cool; I've been wondering whether it was possible to make any of your own metal-clays from metals less dear than silver. This describes both why it's difficult and how to do it anyway. (next up, Aluminum?)

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