It Survived Cone 10
Most of the wild clay I've tested failed somewhere along the way. This one made it through cone 10.
For the first time, a Utah wild clay I processed came through a full cone 10 firing structurally sound: no cracking, no unusual warping, a clear ring and no chalky foot. It isn't ready for production. It still needs shrinkage numbers, handle tests and a salt firing. But it passed the first gate.
- Same process as always: dug, dried, slaked, screened twice, dried on plaster and wedged
- Small test cylinders, no handles or thin rims, fired with a normal load
- Next: exact wet to fired shrinkage, handles, absorption, and salt
I didn't expect it to
Most of the wild clay I've dug and tested here has failed somewhere: cracked rims, warped bases, too much shrinkage, promising at bisque and disappointing at maturity. Cone 10 is not forgiving. This one made it through.
The same process as the others
It got the same treatment as every other clay. Dug, dried and slaked down in buckets. Screened twice to remove gravel and organic material. Dried on plaster. Wedged until it felt workable. It wasn't especially smooth. A little short, slightly sandy under pressure.
I threw a few small cylinders first. No handles, no thin rims, just forms meant to test structure. I let them dry slowly, compressed the bases carefully and trimmed clean foot rings. Honest shapes that would show movement if it happened. They went into the kiln with the usual mix of work, no special treatment.
Where weakness shows
Cone 10 is where things reveal themselves. The clay tightens, iron saturates, fluxes activate. If there's a weakness in the body, that's when it appears: bloating, dunting, stress cracks. I've seen all of it.
When I opened the kiln, I went straight to the test pieces. They were intact. No visible cracking at the base. No warping beyond what I'd expect from a natural clay. The color deepened into a warm, iron-rich brown with slight speckling where minerals concentrated. Not flashy, but mature and dense.
The real test wasn't visual
I checked the ring: a clear tone when tapped. I checked the foot for vitrification: no chalky feel. I ran water tests to get a sense of absorption. Early signs are promising. Not laboratory precise yet, but far from underfired.
That doesn't mean it's ready for full production or that I'll throw thin mugs with pulled handles tomorrow. The shrinkage is still on the high side and I need exact wet to fired percentages. I need to test it with handles, where stress usually shows. And I need to see it in a future salt firing, because sodium vapor can tighten a surface beautifully or exaggerate flaws instantly.
Earned, not romantic
Most wild clay conversations stop at the romance of digging something local and turning it into a pot. At high fire, survival is the first gate. If it can't handle the heat, the origin story doesn't matter. This one didn't blink.
It doesn't replace the commercial bodies I rely on. Not yet, maybe not ever fully. But it opens a door. I'm not interested in novelty batches labeled local clay for marketing. If this material keeps proving itself in daily use and the dishwasher, it earns its place. Until then, it stays in testing.
When a test piece comes out of a high firing, tap it with a fingernail and listen. A clear ring usually means the body matured. A dull clunk can mean underfiring or a hidden crack. It's a free test that takes two seconds.
It's still early, but this is the first time a local clay didn't blink at cone 10. If it keeps proving itself, you'll see it in future releases.
