Copper Clay Tips from Arlene Mornick

19 Jul 2011

Since I first discovered it about ten years ago at a craft trade show, metal clay has been my favorite medium ever, for jewelry making or any other craft. I can't talk about it without saying the word "magic" over and over.

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I thought silver metal clay couldn't be topped, but the addition of new clays such as copper and bronze in recent years has made me love it even more--plus they are more affordable than the silver, so I get to use my favorite medium more often!

And it just got even better, with the publication of Easy Metal Clay, our new special issue all about metal clay, published by the editors of Lapidary Journal Jewelry Artist magazine and featuring the work of metal clay pros and faves Hadar Jacobson, Tamara Honaman, Noël Yovovich, Arlene Mornick, and more. Now I've got a great new resource with over two dozen projects to inspire me, and it has all of the metal clay tips, firing schedules, techniques, and other metal clay information I need in one spot.

The basic processes for working with the newer clays are nearly the same, but each one has some little nuances that pros like Arlene (who is a Master Instructor for Art Clay World USA) have discovered that will save you some time and money. Here are Arlene's tips for working with, storing, and firing copper clay.

Storing, Firing, and Finishing Art Clay Copper
By Arlene Mornick

I've loved working with silver metal clay for more than ten years now, and I particularly enjoy the opportunity to experiment with new metal clays as they hit the market. Art Clay Copper, a new generation of copper clay, requires only thirty minutes of firing on an open kiln shelf for completion of a project.

 
 Spacer 10x10 pixels Knead the clay inside cling wrap and store it in an airtight container.

The product is similar to the newer silver products (Low-Fire Art Clay Silver and PMC3) in its basic forming steps: shaping, molding, carving, texturizing, drying, pre-finishing, and firing with resulting shrinkage (8-10%). There are some differences, and here you'll find helpful information in learning to use the newer copper clays.

When Oxidation Occurs
Unlike their silver counterparts, copper clay products are subject to oxidation, which may occur in three ways during use. Here are the conditions under which it occurs, and ways to minimize or avoid oxidation for each.  

  • Leaving unused clay uncovered and exposed to air: The exposed portion will form a black, hard surface. If this surface is very thick, cut it away with a craft knife until you see the original copper clay color. If the oxidation layer is very thin, knead the entire piece of clay until the copper clay color is consistent throughout the piece. Knead the clay inside of cling wrap and not with bare hands. To avoid oxidation of unused clay, keep the clay wrapped in layers of plastic wrap inside an airtight container.
  • Cooling of the piece immediately after firing: This oxidation is unavoidable, but if the piece is removed from the kiln with tweezers or tongs and quenched immediately with water, most of the oxidized layer will peel off. Exercise caution; the piece is extremely hot, so use heat-resistant gloves. Small chips of the oxidized layer may fly into the air, so wear safety glasses. Oxidation left on the piece after quenching may be removed with pickle or heat from a torch.
  • Long-term effects on the finished piece: A thin oxidation layer forms, which can be removed with a polishing cloth and, if necessary, metal-polishing chemical products.

Deborah Read's Dichroic Mosaic Bracelet Spacer 10x10 pixels
From Easy Metal Clay: Deborah Read's Dichroic Mosaic Bracelet  
   
Pickling to Remove Oxidation After Firing
After quenching fired pieces, place into pickling solution to remove the oxidized layer on the surface that results from firing. The amount of time the piece remains in the solution depends on the depth of the oxidation layer and may vary from ten minutes to two hours.

Pickling solutions should be kept warm while in use. I use a very small CrockPot. Its interior ceramic surface prevents any chemical reaction that may occur when using base metals with pickle. After pickling, neutralize the pieces with a solution of 1 teaspoon baking soda to 6 ounces of water.

Spacer 10x10 pixels Hadar Jacobson's Gradient Pendant
  From Easy Metal Clay: Hadar Jacobson's Gradient Pendant
Remove Oxidation with a Butane Torch
As an alternative to pickling, use a butane torch. Hold the piece in a pair of locking tweezers, heat the piece to a red glow, and continue heat source until the black oxidation disappears and the copper begins to turn other colors, including variations of green and blue. Quickly quench. The black color caused by oxidation will be removed and the patina colors will remain.

Kiln Firing Guidelines
These firing instructions are specific to Art Clay Copper. Other low-fire copper clays may have different firing instructions according to the manufacturer.

  • The piece can be fired in a kiln at 1778 F degrees. Maintain this temperature for thirty minutes.
  • Allow the kiln to cool to 1500 F degrees and remove the fired pieces from the kiln with tweezers or tongs.
  • Quench immediately with water, which will help remove most of the post-firing oxidation layer.

Jean Whittington's Spinning Rings Spacer 10x10 pixels
From Easy Metal Clay: one of Jean Whittington's three Spinning Rings  
Butane Torch (Micro Torch) Firing Guidelines
Use a small butane gas torch to fire Art Clay Copper projects. I have had success with pieces that weigh ten grams or less.

  • Place the completely dry piece on a firing brick. Switch on the torch and direct the flame on the piece at a 45-degree angle from a height of about 2 inches. The flame should be rotated directly on the piece over the surface to heat evenly.
  • Burning away of the non-toxic organic binder will produce a little smoke and flame. When the piece begins to glow red, start the timer. 
  • Continue to heat the piece for the recommended duration. Alter the distance of the torch from the piece to maintain the glow but not overheat the piece.

Spacer 10x10 pixels Noel Yovovich Bold Rolled Bail
  From Easy Metal Clay: one of three bails by Noël Yovovich
Finishing
Apply the same brushing and polishing techniques to copper clay as with silver metal clay: steel brush, burnisher, and tumbler.

Combining Copper and Silver

  • Copper will sinter after 30 minutes at 1778 F degrees and silver after 10 minutes at 1450 F degrees. Copper melts at 1985 F degrees and silver at 1760 F degrees. Always fire copper components first to copper firing schedule and quench pieces as outlined above.
  • Copper and silver do not sinter together. The already-sintered copper piece and the still-soft silver clay are placed together so that they will lock together during a second firing at the silver firing schedule. Shrinkage of the silver clay during firing causes it to clasp and hold the copper piece.
  • Quench piece after the second firing. Clean with a stainless steel brush and pickle pieces as necessary. Finish with a rotary tool, files, and polish as needed.

Please note that I have experimented with firing both clays together in one step and I have been successful in the following schedule: fire to 1650 F and hold for two hours, then quench as recommended above.

Copper Clay Tools
I use the same tools for both clays. Simply wipe the tool or work surface clean before switching clay types. The only tools that I am cautious about sharing between clays are my files.

- Arlene Mornick

Kathleen Bolan's Bamboo Earrings Spacer 10x10 pixels
From Easy Metal Clay: Kathleen Bolan's Bamboo Earrings
Whether you're new to metal clay (do it! do it!), or you love metal clay as much as I do, you'll love Easy Metal Clay as much as I do, too! It's full of inspiring designs to make with silver, bronze, copper, and even steel metal clays plus crystals, gemstones (including how to set them), wire, glass, chain, and even ink.

I particularly enjoyed the "Clay by Clay" comparison chart that helps you choose the best metal clay for you and your project. It includes lots of great time- and money-saving information about each type of clay, how to fire it, its shrinkage rates, and more, so you can better know your medium as you work with it. Valuable stuff! Pre-order or instantly download Easy Metal Clay and work your own magic! 


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