Make Your Own Shibuichi Clay

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Shibuichi is an ancient Japanese alloy of copper and silver, with the percentage of silver ranging between 5% – 25%. There is a very informative article about this alloy in March 2010 issue of Art Jewelry Magazine by Lee Rumsey Haga, which I highly recommend.

I have been often asked about combining different metal clays together, so I decided to try. I made “Shibuichi clay” of 5% silver and 95% copper, using mixed Quick-fire copper and PMC Plus.

One way to measure is to use a scale. To make 10 grams of this type of Shibuichi clay, mix 0.5 grams silver clay with 9.5 grams copper clay.

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If you don’t have a scale, roll the clays into layers of equal thickness. For example, roll each clay between two stacks of 4 cards.

Next, use a straw or a another cutter to cut one circle of silver and twenty circles of copper out of the layers.

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To make an alloy with 15% silver, cut 3 circles of silver and 17 circles of copper.

To make an alloy with 25% silver, cut one circle of silver and 3 circles of copper (use a bigger cutter, of course).

Then mix the clay with your fingers, and roll it under the rolling pin over an over until you get a homogeneous color.

I pressed the clay against a texture with high relief.

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I fired it with a torch for 6 minutes from the moment the binder had burnt off, and immediately dipped in water.

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I found that torch-fired Shibuichi clay is stronger than torched-fired copper clay.

I also tried it in a kiln. Using my new firing method as described in my previous posting, I fired it for 1:00 hour at 1470°F (800°C) in my top loader kiln. In a front loader, fire at 1550°/843°C.

At this point, you can either start playing with patinas or, if you want to clean the piece first, dry it thoroughly on a warming surface.

Shibuichi is very receptive to patinas. Here are some examples:

Rust

Rust

Blue

Blue

















Purple

Purple

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Blue-green

Blue-green














Heat patina

Heat patina

The last example was done by gently heating with a torch and dipping in water when the desired color was achieved.

Since metal clay is so porous, you will need to apply the patina more than once. I placed the piece on my warming surface and applied it with a brush. At first the liquid was totally absorbed into the metal. With every further application the colors developed more and more. Sometimes they developed after I removed the piece from the warming surface and let it cool down.

When the color was achieved and the piece was dry, I sanded the high part of the relief, first with 220-grit sandpaper, then with 400 grit.

The patina can be sealed with lacquer spray or with sealers from the sources below.

Sources:

Rust, blue and green patinas are available from hardware stores, or from craft stores such as Blick and Michael’s. The series is called Sophisticated Finishes.

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Another source is www.sculptnouveaux.com. They also have different sealers and their products come with full instructions.


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