Dec 20 2011

Project for the Holidays

So Jenny asked how I made the swirl earrings that accompanied my previous posting.


If you have some free time over the holidays, here is the project. I have made it twice more, once with a combination of copper and White Bronze, and once with a combination of copper, bronze, and the new Quick-fire Steel XT.

But before I turn you loose with the project, here are a few announcements:

1. A workshop in Sierra Madre, California, was added to my schedule. The dates are June 2-3, 2012. Contact: at MASSC.

2. The “architectural” intensive at my studio is full. Next intensive is in March. Next year’s workshops will combine architectural designs with patterns of color, as shown in the photo below.

Architectural Rings

3. Because of a scheduling conflict, Holly Gage’s teaching engagement at my studio will only include the workshop “Jewelry that Rocks.” The dates are February 13-14.

Green-Red CD Necklace

Now for the project.

Swirls Copper WB


1. Make a disk for your extruder with a square hole, 3×3 mm. You can also use a circular hole of about the same size.

2. Make the stack and extrude it.


3. With your fingers taper the end of the cane (the one that came out of the extruder first). Coil the cane around itself. If you used a circular hole, flatten the coil now.

4. Repeat step 2. Coil the cane in the opposite direction. Do not get tempted to extrude one long cane for both earrings!

5. After drying, sand one or both sides of the coil until the pattern shows. If the earring becomes too thin, add a copper backing layer.

6. Sand the earrings into shape and size with a nail polisher.

7. Fire.

Have fun!

Dec 19 2011

Combining the New Sterling Clay with Copper Clay

I have been asked by PMC Connection to test the compatibility of the new sterling clay with copper clay. Here is my report, which includes instructions for applying projects from my book Patterns of Color in Metal Clay to a combination of sterling and copper, as well as some suggestions for avoiding disasters and saving material. Please note that I have not tested the new sterling clay on its own, just the way it works with copper clay.

Firing Temperature

When firing silver clay with copper (and this applies to both fine silver and sterling, and copper clay in general), the firing temperature should be lower then the manufacturer’s suggested temperature. Fire according to the White Bronze schedule (Schedule C in my Instruction Manual, p. 27). I fired sterling and copper at 1320°F/715°C in a brick top loader, which would be equivalent to 1400°F/760°C in a front loader, and my pieces melted. This temperature is way below the recommended one for the new sterling clay.

Melting at 1300°F

The piece on the top right was not fired at this temperature.


Inlay Ring

The inlay ring in the photo above was made with copper clay and the new sterling clay. Both clays were fired together at the low temperature for White Bronze. The ring shrank 3 sizes. Because of possible reactions with the skin, I chose to make the shank from sterling. I noticed 2 problems:

1. As you can see in the photo, some copper made its way into the inner shank, probably while I was smoothing the inside with a wet finger. This could not be detected prior to firing.

2. Although I was able to hammer the ring into shape on a mandrel without breaking it, I am not sure how strong it is because it was fired below the recommended temperature. Theoretically, the shank could have been fired first at the high temperature for best strength. In practice, since the shank was not going to shrink again in the second firing, the surrounding layer would probably crack while shrinking around it. The same thing would have happened if the shank was made out of copper.


Silver Over Copper Clay

Copper was fired first. Silver was wrapped around and fired with a torch. It worked just fine.

Wraparound 2

Silver was fired first, copper strips were wrapped around it and fired in carbon.

Wraparound 3a

Wraparound 3

The copper strips sintered, but always split and came off. At first I thought it was a shrinkage issue, but eventually I started to suspect that some rejection reaction was taking place. This hunch was supported by the recent experiments that I have been doing with combining the new sterling with copper.

Mokume Gane Patterns

In these patterns silver and copper have to be fired together, without firing one of them first. I have tried it before with home-made sterling clay, and it worked just fine. You can see photos on p. 112 of my above-mentioned book. Here is my first try with the new sterling clay:

Frame Separating

Square Earrings Cracking

I noticed the cracking and separation while I was still burning the binder on a stove top. It took 4 more rounds of patching and firing to bring the earrings to a decent state:

Sterling 2

This has never happened to me before when combining either fine silver or home-made sterling sterling with copper. However, before rushing to conclusions about the new sterling clay, I remembered what happened when wrapping copper around silver, as shown above. As you can see in the photo above, the mokume gane pattern is wrapped with copper. Perhaps it was the rejection reaction that I suspected four years ago.

So, I tried pieces without framing them in copper. I watched them on the stove top and no cracking occurred.


Square Earrings

Round Earrings

Because of the high shrinkage rate of the new sterling clay, I fired the above rectangular earrings with my Traditional (Flex) copper clay, which shrinks more than the Quick-fire version. The circular earrings were fired with Quick-fire copper. The shrinkage rate of both pairs of earrings was the same. However, while the surface of both was not flush after firing and required some grinding, the Traditional copper was easier and quicker to grind.

By the way, with home-made sterling clay the shrinkage rate of mixed pieces is very low.

How do we make sure that the outer layer is always silver and not copper?

Most of the mokume gane patterns introduced in my book are created with a clay extruder. The instructions are always to stack the circles with the copper closer to the opening to the extruder. That way the extruded cane always has copper on the outside. When working with copper and silver, make sure the silver circle is closer to the opening, so the extruded cane is silver on the outside.

How to Stack

Silver Cane

Making sure that the outside layer is always silver sure helps a lot. However, cracking did occur in all my experiments, not in the first phase but in the second. All pieces required repair and re-firing, although not as may times as when the copper was the outside layer. Cracking did not occur when I used home-made sterling clay.


How to Save on Silver

Naturally, when sanding and filing pieces from copper and silver before firing, the silver powder gets mixed in with the copper powder. I have been saving the powder, as well as mixed clay that was leftover in the extruder. I have used this clay for making backing layers for the pieces and for patching in hidden spots. The earrings in the following photo were backed with mixed clay:


Back of Swirls

The backing layer has a yellow tint. Also notice the pits. I was not able to remove them, even with heavy-duty sanding.

Mixed Clay

The circle on the left is what was left over from the mix after I’d finished the experimentation. It has a pinkish color.

Just as a point of interest, I have noticed that you can mix up to 35% copper in fine silver before any color change is detected in the fired piece.

Dec 1 2011

Updates to My 2012 Class Schedule

Four more workshops have been added to my teaching schedule for 2012:

March 17-22
5-day intensive at my studio in Berkeley, CA 510-528-4183.
Sign up here:

April 2-5
Montreal, Canada
Jocelyne Robertson
Phone: 514 990-0441

Note: 4 workshops are scheduled in Canada this year: one in Montreal, one in Edmonton, and two in Vancouver.

June 26-April 1
Kvernes, Averøy, Norway
+47 71514100

October 12-13 (beginner class) and 14-15 (advanced class)
Studio 34 Creative Arts Learning Center
Rochester, NY
(585) 737-5858

Please look at the file “Hadar’s Travel-Teaching Schedule” (also available in the right-hand pane of this blog) for the full schedule.