After firing the metal clay pieces it is time to burnish or polish them. They still look like clay until you have polished them. There are many ways to polish - wire brushes, spoon, polishing papers (very fine sand paper), steel wool, agate burnishers and rock tumblers to name a few.
To Pickle Or Not To Pickle?
Everything I read about torch firing copper clay said that you had to pickle the piece after torching. I spent about 45 dollars purchasing the necessary pickle equipment (copper tongs and pickle pot, sodium bi-sulfate compound). However, my torched pieces had very little fire scale on them and I did not pickle them, as I didn't feel it was necessary. Plus, I usually like to patina or antique them anyways, so the little bit of fire scale there, will just add to the antiqued look.
Please note: As I fired the pieces, I kept the torch on the piece as I picked it up with my pliers and continued to heat the piece until I submersed the copper into my quenching water. Keeping the heat on the pieces as long as you can will reduce the amount of fire scale they get.
Lesson 1: It is not mandatory to pickle torched copper clay.
Then I read how toxic pickle solutions are - how they need to disposed of properly at a hazardous waste facility, how it can eat holes in your clothing if splashed upon, burns skin etc.... I have a toddler in my house, do I really want this stuff around? There are a couple more environmentally friendly alternatives to sodium bi-sulfate compound, such as citric acid, that I will try before using the traditional pickle.
Burnishing With A Wire Brush
Some people suggest using a steel brush while others suggest a brass brush. I tried both, and found that the brass brush turned my copper pieces a brassy gold color. The steel seemed to bring out the copper color, so that is what I continued to use. In the photograph below, the small circle was burnished with the brass brush, the flower with the steel brush and the heart is only have burnished, to show you the difference. After I finished these pieces, I read someone who suggested brushing under running water, with a little soap. These pieces were brushed dry, next time I will try brushing with water.
Lesson 2: For copper burnishing, begin with a steel brush.
Next I used 0000 grade steel wool. I highly suggest using a ring clamp to hold your piece (if it is flat) while using the brush and steel wool. Those two polishing tools can really wreak havoc on your fingertips.
Lesson 3: Use your ring clamp.
I used liver of sulfur gel to patina my pieces. I let some of the pieces oxidize longer than the others. I wanted them all to be different. I also wanted to experiment to see how this copper clay took the patina. For more information on liver of sulfur patinas, see this article here.
Here are my pieces after being in the rock tumbler (with stainless steel shot) for two hours. I am happy with the result - not bad for my first attempt, yet far from perfect. But I have learned a lot in the process. Hopefully you can learn a little from my mistakes as well.
The heart in the top left corner did not receive a liver of sulfur patina. The others did, for varying lengths of time. The ring at the bottom is of pure copper wire, just to illustrate the color differences.
I would love to hear what you think!