Adjustable Rings from Metal Clay – Yes, No?

Yes! I’ve been often asked if the metal is somewhat workable after firing, and wanting to be better safe than sorry, I’ve always said “No, do all fabrication before firing!” I still do all my fabrication before firing, but I also want to have the fired pieces be a little adjustable. What if a ring, for example, doesn’t come out the size I intended it to be? As you may have noticed, many factors can affect the shrinkage of a ring, including size, thickness, firing schedule, and firing environment (what else is in the kiln).

So I experimented with a a few open rings.

Rings open

Two of them are Friendly Brilliant Bronze, one Friendly Copper and one Pearl Grey Steel. The copper one is 6 cards thick; the rest are 4. All rings distorted significantly during firing. They were all hammered into shape over the mandrel, with no cracking. They were then closed with two fingers.

Bronze Rings overlapping

Copper and steel closed

To re-open them I needed to use the mandrel. The hardest to re-open was the copper (the 6-card-thick one). So far they have been opened and closed a few times without reaching the point of metal fatigue.

Friendly Brilliant Bronze was fired according to its regular schedule, with 1:30 hours hold at 1000°F. The copper and steel rings (I made a few of each) kept breaking until I raised the temperature to 1850°F (my kiln is brick, so that means 1900°F in a muffle kiln).

Just to see what would happen, I fired copper and Pearl Grey Steel at 1900°F (brick). They came out fine, although harder to bend. You may ask if this temperature is not too close to the melting point of copper. The answer is no, since the temperature displayed on the controller is always higher than that inside the carbon.

I am now firing both copper and PG Steel at 1950°F. Will report back.

That brings us to cuff bracelets.

Cuff open

Cuff closed

On hand

This one was made with Friendly Brilliant Bronze, 6 cards thick, and weighs 35 grams. It was opened and closed a few times in order to slide it over my arm. I am currently working on an open copper bracelet. A test firing showed that the copper bracelet, when fired at the right temperature, can be opened and closed and the open parts can be moved up and down.

In the kiln now: Low-shrinkage Steel XT ring at 1950°F. At a lower temperature Low-shrinkage Steel XT cracked when bent. I still need to test a few other clays. Stay tuned!

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