Metal Clays--Tips for Working with Copper and Bronze Clay
Bronze and copper metal clays are wonderful materials and yield great designs with very warm and rich tones. The clays are similar to gold and fine silver metal clay in that they are a clay material comprised of fine particles of metal, an organic binder and water; they can be shaped, rolled and textured, and when fired you have pure metal.
When working with bronze and copper metal clays, there are a few guidelines to follow which will help your success with the materials:
- Tools used for working with bronze and copper metal clays, which cannot be washed (like jeweler's files), must be dedicated to working with bronze and copper metals to avoid cross contamination between them and any other metal clay.
- Bronze and copper metal clays must be fired in an oxygen free environment in a kiln to achieve a proper sinter (fusing the metal particles together with the use of high heat).
- A stainless steel pan and coal carbon or coconut carbon are ideal tools for creating this environment
- You should wear a mask when working with the carbon to avoid inhaling the fine particles and dust
- Everyone's kiln will yield different results
- Results from firing to firing, within your own kiln, may vary
- It is best to test your kiln by firing copper and bronze test pieces prior to firing the work you have spent time on, to determine what firing schedule works for your kiln
- It is best to fire the copper and bronze metal clay pieces as high up in the chamber of the kiln as possible
- Raise the pan inside the kiln by placing it onto stacks of pieces of kiln shelves or kiln feet
- There are various firing schedules being used--Hadar Jacobson's firing schedule has worked well with my kiln, which is a front loader with a thermocouple located in the back wall, like the Paragon kiln shown, and has a programmable controller.
Pour carbon into the pan until it is a little more than 3/4 full.
Place pieces into the carbon so they are positioned along the back wall and sides of the pan; avoid the front of the pan for front loading kilns as this area does not necessarily achieve the full temperature needed for a good sinter.
Program the kiln to ramp up at the speed of 1,750 degrees Fahrenheit to a set temperature of 1,100 degrees Fahrenheit; hold for 30 minutes.
Let the kiln come down to room temperature.
Carefully remove the pan from the kiln.
Remove any carbon that turned white during the firing.
Using the same type of carbon, add more to the pan, filling to the top, although not so full the lid doesn't sit flush with the top of the pan.
Place the lid on top.
Place the pan back into the kiln.
Ramp up at full speed to 1,550 degrees Fahrenheit and hold for 3 hours.
Remove the pan using the firing fork or let the kiln come down to room temperature.
Remove your test pieces.
Try to break one of the test pieces to see if you achieved full sintering. If the test piece breaks, you have to start over.
We would like to share some of the customer comments we received in response to the article, "Metal Clays--Tips for Working with Copper and Bronze Clay," featured in a newsletter. Please keep in mind that the comments expressed below are those of our customers and do not reflect the views of Fire Mountain Gems and Beads.
"I enjoy receiving your online newsletter, I read it from top to bottom and look forward to the next, same thing with the catalog, I look at it often and make wish lists."
"I found the info shy of giving any real and useful info to the reader. Removing pieces and then filling the pan and firing for 3 hrs. More on a few of the pieces. Look at the current info that has been given to the clay community and it doesn't jive. This info would be great if it is kept up to date."
"I love the latest newsletter about metal clay. I have been thinking of learning how to use it and your newsletter answered some of my questions. Thanks so very much!!"