Sterling Silver with Hadar’s Clay™ Quick-fire Copper

Congratulation to UK metal clay artists on making silver clay that can be Hallmarked 925 silver! I was glad to hear about this via email while teaching in Ohio, and couldn’t wait to read the article in Metalclay Artist Magazine. I was surprised to read, though, that the testers had no success with my clay. So, for my customers in the UK, I tried. I made it with PMC+, since that’s what I had at the moment. I measured according to the instructions and blended. The consistency was nice and not sticky. After a night in the refrigerator it had a yellowish film on it:

I kneaded it a little and it regained its consistency. The ball in the photo weighs 20 grams. I made two rings and have some left over.

Then I made a ring. I used a wooden dowel with ring size 9.

.

I made the ring around it, 2 cards thick (with fine silver I have never done a ring less than 4 cards thick). I removed the ring when it was half dry and continued drying. After drying, it shrank and did not fit the dowel anymore.

I placed the ring in a mixing bowl half full of carbon and started heating it with a torch.

Once the binder caught fire, I removed the torch and let the binder burn on its own. The photo below shows the burning in a second experiment that I did, in a mini-kiln made from fire brick.

Once the fire died, I covered the ring with carbon and placed it in a front-loader kiln. (I assumed that this is the type of kiln the testers used.)

I fired for 1 hour at 821°C/1510°F. Here is the ring, right out of the kiln:

The ring shrank to size 6.5 and appears to be very strong. I oxidized, sanded, and polished.

(Not a masterpiece, I know; it was just an experiment.)

Firing the other ring in a top-loader inside a mini-kiln required a lower temperature. I fired a little lower than 821°C/1510°F, and still it seemed that the silver started to melt. I sanded it with a heavy-grit sanding band and it’s ok now. I would suggest starting by test-firing in a top-loader as low as 1400°F/760°C.

t-2 ri

So why didn’t it work in the UK? My only guess is that the testers may have used my Traditional Copper powder, not the Quick-fire version.

I also have a suggestion for more accurate measuring. When the two clays are mixed with water, there is no way to compare the amount of water in them. For example, one of the clays may be dryer than the other, and will weigh less than it would have if it were as moist as the other clay. Dry the silver clay that you are about to use, until it contains no water at all. With a dedicated coffee grinder, grind it to a powder. Then weigh the powdered silver and the Quick-fire Copper powder and mix them together. Then add water to the mix.

In any case, I am very happy for you over there on the other side of the pond! Hope to meet you again sometime!


Leave a Reply