Sunday, 27 May 2012

Sunday Project: Copper & Bronze Clay

Actually this is more of a full weekend project.
Ever since I first heard of metal clay I have been intrigued. metal that you can mould and shape like normal clay? Doesn't that sound so much easier than hammering, sawing and soldering let alone casting metal?

I had to give it a go. I've read around on lots of blogs about this and it sound like the silver clay is much easier to work with, especially if you want to torch fire - I don't have a kiln.
In fact I read several jewellers frustrated accounts about torch firing copper and bronze and that it just doesn't work.
A bit apprehensive I thought it might be time to take a real course instead of my usual diet of DVDs, blogs and Youtubes, so I signed up for a day with Natalia Colman, who was just about the only teacher I could find with copper and bronze on the menu.
I had a great Saturday. Natalia is a friendly, thorough and patient teacher, and the little group of four students was just right and great fun.
We went through the basics of conditioning the clay, rolling, stamping, shaping, moulding and so on, but it was the firing that I was mostly interested in.
The copper performed without a hitch both in the kiln and under the torch. It came out beautifully, but with considerably more firescale and oxidation on the kiln run. Nothing my Dremel couldn't fix, but it did offer a good deal more work on the finishing - obviously firing lots of pieces at once makes up for that, but if anyone has tips on how to avoid a thick crust on the kiln result then I'd love to hear about it.
I loved playing with the clay and I if I am going to make any larger amount of clay jewellery, then I think the kiln would be handy. By torch each piece has to be held at the right temperature for 7-8 minutes and it won't work with larger pieces.

The bronze was a lot more temperamental with lots of pieces breaking and down right 'exploding' in the oven. I have no idea why this is - calls for more experimentation. Under torch it was a bit more reliable, but still went wrong on one piece which simply did not fire all the way through despite being quite thin.

Above is my own attempt with the torch today. You can see it in all the stages. Another issue as you might be able to see is that the bronze comes out with a more matte colour and that it cannot be polished to a high shine like the copper can - even is sanded down to micro fine.
 Plus when it is finished the colour looks more like copper than bronze to me. I wonder if that's a comprimise the manufacturer has to make to get bronze to handle in clay.
We used the Creative Metal Clay brand - also known as Prometheus.
Here you can see a bronze leaf and a copper face. 
Bronze & copper comparison - electric light and sunlight
Don't they look awfully similar? Even holding the pieces in my hand there is hardly a difference in colour. I'm a bit disappointed with that. I wonder if other brands come out the same.
Given all the problems we had with the bronze I don't think it's worth it, really.

But all in all I am really pleased that the torch firing actually is easy to get right, which means I can experiment a lot more and really be sure about the clay before I invest in a kiln.

Addition to this post can be read here