Setting Cultured Opals in Silver Metal Clay

Setting the Opals is straightforward. The Opals have been set in Metal Clay with 18% shrinkage with no ill effects. If you have higher shrinkage clay, a looser setting is recommended to allow for shrinkage. This is no different from any other gemstone and Metal Clay and is a good rule of thumb.

 

Clean well with alcohol on both sides before putting it in the kiln. Set the Firable Opal with an azure — a hole behind the stone is recommended to show off its beauty. Seeing the kiln white through any translucent stone will look cloudy or milky in Metal Clay, and this is also a good general practice for all stone settings.

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Re-firing these Cultured Opals

Proceed at your own risk. We've had mixed results. A second long 2-hour cycle at 1650ºF was too much for a small stone and it cracked. Another larger Cultured Opal fired twice with a short 30-minute firing at 1650ºF worked. What's the difference? Either the size of the stone or the length of the firing or both affected the results. More tests are needed on this topic, and we'll report back. Our best guess is when you refire to repair cracks, fire at shorter times, and temps when possible.
 

Tumbling in a Tumbler

How to tumble them safely.
Use Grafix® Incredible White Mask Liquid Frisket, a liquid latex that looks like a thin milky liquid. When dry it is waterproof and can protect a stone from damage in a tumbler.
- Use a pin tool or small stylus to apply the Frisket
- Apply enough to cover the stone front, then back.
- You may add more after the first layer dries especially on the pointed side of the stone or cutlet of a faceted gem.
- Add enough to create a “cushion” of latex versus a thin coat.
- When dry it should look more cloudy-translucent versus milky.
- After it comes out of the tumbler, just peer off the frisket.
- Wipe off tools immediately after use.
- You can speed up drying on a hot plate.
This experiment was done with a vibrating tumbler and mixed stainless steel shot.

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Using a Patina such as Liver of Sulfur

Liver of Sulfur or (LOS) does not affect the stone, however, if you are working with a translucent stone it might affect the appearance when you see the dark LOS behind it. Again, Use Grafix® Incredible White Mask Liquid Frisket, as mentioned above as a "resist" to prevent the LOS from getting on the metal where ever you don't want it to be.

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Rotary Tool Finishing

Use quality masking tape to protect the Cultured Opal. Burnish the masking tape down so it really sticks to the Opal before using a rotary tool to do any polishing. These Cultured Opals are a bit more resilient than natural opals, but abrasive wheels will dull their shine. if you happen to scratch it, a muslin wheel with diamond paste should remove it, if not too deep.