Wednesday, March 24, 2010

Copper Clay Update

If you read the previous post you'll see that I was soooo happy with my copper clay pieces. Now I'm thinking, not so much.

It appears that many of the pieces did not sinter. When I drilled holes through some of them in order to attach jump rings, there was the dreaded brown powder, meaning that the outside was a nice, solid, shiny copper but the inside was still powdery. And, a couple of them had parts attached with slip (watered down clay used like glue) and these parts popped off. In the first photo above you can see that the bail broke off. When I tried to drill a hole, it just crumbled. Since this was all experimental, I decided to try breaking one with my hands, and sure enough, "snap"! Broke in half like a saltine cracker. In the second photo you can see the one I intentionally broke. The center piece was put on with slip (it came off) and you can see the brown powder very clearly. I can rub it off with my fingers. This is not good. Fully sintered metal clay should be as strong as sheet metal. And, I want to be sure that none of my customers would ever encounter breakage.

I suspected several things that could have caused this. 1) I had too many pieces in the firing pan, causing the heat to be distributed unevenly. 2) I should have done a 2-phase firing. And 3) The kiln did not get hot enough.

So, I went online to my Etsy Metal Clay Team colleagues to see what their experiences were. Kelly Fehr disputed #1. She has fired as many as 60 pieces in a single firing, so I don't think that was it. She also says she has no problem using slip if a little lavender oil is mixed in with it.  Lorena Angulo makes large sculptural pieces out of copper clay and she told me that she has success when firing them at 1770F. I followed package instructions and only fired to 1700F. It now looks like that extra 70 degrees makes a big difference. Lora Hart was the one who originally told me about the 2-phase firing. First you fire the pieces on an open kiln shelf, then transfer them to the stainless steel pan with the activate carbon and fire them again. She was helpful in reminding me that this material is VERY new and that when silver metal clay came out around 15 years ago many artists had failures until the formula was improved. So, we're all esentially experimenting with this stuff.

I'm disappointed that my things didn't come out as planned, but it was a good learning experience for very little money, and Debbie, Torrey and I sure had a lot of fun with it last Sunday. I may try firing the remaining pieces from this first batch again and see if that solves the problem. I still have a little copper clay left in the package to use up and I'll do them all at once.

Here's a some successful copper clay pieces by Kelly and, Lorena. Lora is taking a break from her Etsy shop right now, but here's the link to her wonderful blog: Such and Such

Om Pendant by Kelly Fehr. Click HERE to go to the Etsy listing.

Copper Lines earrings by Lorena Angulo. Click HERE to go to the Etsy listing.


Cherylyn Bredemann said...

Hey, Zoe -
Sorry for your disappointment. I had a similar experience last month. I haven't try another batch just yet. But I was equally disappointed.
Here's my post, if you care to read it.

But I still love the bronze clay and have had a lot of success with it.

~ Lora Hart Jewels ~ said...

Aw, thanks for mentioning me Zoe. I try to stick my nose in ... errr... help where ever I can. ;D I know you'll figure it out. It just takes time sometimes.
L ~

Lore said...

Thanks for mentioning me Zoe.
As you said, this medium is very new and we are still experimenting with the clay. I think is very important for us to keep on trying ;-).
I found the way to fired my work and it may be totally different than what it is working for other people because everybody has a totally different style in their work.
We all need to keep playing until we find the perfect firing for our work.
I also posted about my problems with the copper in my blog.

Kristine said...

I like your beautiful jewelry.
stunning photography and inspirational blog.
Greetings from Denmark

Zoe Nelson said...

Thank you for stopping by, Kristine!

SarahSundance said...

Hi Zoe
Am sorry that it didn't work out with your new pieces but in every failure is a lesson which leads us to greater success. Didn't Eddison say he found 700 ways how 'not' to make a lightbulb, before he actually cracked it? I'm not a big MC user but my experience has always been to double fire pieces. Sometimes on the first firing it just doesn't seem to have shrunk enough so I always give a second blast. Seems to do the trick. Good luck with your work.