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!

12 Responses to “Sterling Silver with Hadar’s Clay™ Quick-fire Copper”

  • Maureen Says:

    What a Sterling effort! (excuse the pun)actually the rings are quite impressive for experiments. Very modern.

  • Melody Pierson Says:

    That makes perfect sense!
    However, I couldn’t find the measurements of silver clay and quick fire copper in the blog…
    Maybe these Iphones are getting the better of me.

  • ann schneider Says:

    Fabulous! …..and I really like the rings.

  • Terry Brake Says:

    Hadar, love those “experiments”, rings are very nice! Also, your workshop in OH that I attended last weekend was very useful. I fired some mixed ‘woodgrain’ sticks at home the next day, and they came out well. But my kiln is hot, and made the larger bronze /cu inlays disappeared. Only rough surface bronze, but friends liked them. Thanks for your generous gift of knowledge!

  • Beckie Walker Says:

    Thank you so much for this–great suggestion about accurate measuring via the weight of the clay. I use the coffee grinder suggestion all the time and it works beautifully. Can’t wait to try this!
    PS: Even your test pieces are so artistic–love them! 🙂

  • Cindy Pope Says:


    Thanks so much again for doing the experimenting so we don’t have to. To bad the testers didn’t get some input from you. I’m so glad you got it to work, I just got the magazine but hadn’t read it yet. I think drying the clay is a good idea. I also love the rings they remind me on the one in your clay instructions that always catches my eye.

  • Anneli Says:

    I wondered too why they didn’t succeed in mixing silver with your copper clay. Thanks for the explanation and the experiment!
    Drying the clay before mixing is a great idea! Should make it easier to mix the two together as well.

  • Chris Pate Says:

    Hi Hadar, it’s Chris Pate, I did a wonderful workshop with you at Tracy’s Craftworx last year – remember? I was the lady with the kiln that you punched a hole through the top to vent it! It works perfectly now!! I was one of the testers of the sterling clay that Lisa Cain provided. We did blind testing so didn’t know what the mix was until afterwards. Our samples were with Art Clay copper – Lisa was the only one who tested your clay I think. But thank you so much for doing these tests with your powder – I have some of your fast fire copper clay so will give it a go. The sterling we produced is certainly very impressive when fired – really strong and will enable us to produce much more delicate designs that simply were not possible with the fine silver. Watch this space!!
    Best wishes and hope to meet again.

  • Diane Says:

    You may not call the first ring a ‘masterpiece,’ but I love it! Thank you for all you have taught me through your website and your blogs. I am having so much fun experimenting with copper and bronze clay. I appreciate all the experimentation you are doing for all of us.

  • Lisa Cain Says:

    This is fantastic news Hadar! I’m firing a mix of your Quick Fire Copper/PMC3 powder right now. My mistake was to test the wrong Copper powder-(hangs head in shame….) I grabbed the wrong pot not even thinking I had any ‘long-fire’copper powder here.
    The test strips will be on their way to the Assay Office for Hallmarking first thing Monday. Then strength tests ready for a data chart to be published ASAP. Excellent!
    Please excuse the dumbclutz mistake-my original aim was to share sterling recipes made with as many brands as possible so I am delighted it is possible.
    Thanks so much!

  • Mary Ellin D'Agostino Says:

    I use your copper clays regularly to mix with silver clay (any brand, any formula) and have no problem. I fire longer because I am doing higher copper alloys for the color contrasts. Your 1st generation copper clay will work in a sterling mix if they fire for a longer time (e.g., 4-6 hours). Using the quick fire copper and a low fire silver allows for a quicker firing due to the smaller particle size (or something like that).

    For more on my Cu-Ag experiments, go to
    Mary Ellin

  • Georgie Galante Says:

    Think I missed something…what ratio silver powder to copper powder?