Formula for Beauty: The Geo-Chemistry Behind Rookwood Pottery
By Ben Marks
Some of us look at an eight-place setting of fine porcelain china and see a family gathered for Thanksgiving dinner. Gazing upon a curvaceous piece of art pottery, we immediately picture it up on the mantel, lit by a pin spot and casting seductive shadows on the wall. But when Jim Robinson of Rookwood Pottery looks at a ceramic mixing bowl, a stoneware jug, or even a single piece of architectural tile, he sees rocks.
“Oh, I’m absolutely crackers for geology,” Robinson confirms when we spoke recently. “I was reading John McPhee once,” he says of the famous “New Yorker” writer, “where he talks about how the movement of plate tectonics forces rocks down into subduction zones. When that happens, most common minerals like feldspar melt, but McPhee calls out this one particular mineral compound for its heat resistance—zirconium silicate, what us potters know as zircopax or zircon. Even after being fried inside the earth’s crust for millions of years, zircon doesn’t lose the memory of what it was, which is why potters use zircon to make a glaze opaque. It’s actually zircon’s ability to take the heat that makes it an effective opacifier. So, as I’m reading my McPhee, I’m thinking, ‘Zircon, you dog!’”
Such epiphanies explain why being an amateur geologist is probably not a bad avocation for a glaze chemist, Robinson’s job title for the past seven years at Rookwood in Ohio, and his passion for four decades before that as a “clayworker” (his term) in Oregon. That said, “glaze chemist” doesn’t begin to describe the full extent of Robinson’s role at Rookwood. Sure, he’s developed hundreds of glazes in his relatively brief time there, but he also designs vases, formulates recipes for the clay itself, and generally pitches in when things go haywire. “I work my butt off,” he says with undisguised pride.
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