Real Dirt About Clay

Since the earliest times, humans have had a close association with clay: in building, in pottery, even in medicine. It’s an important part of North Carolina history. Get the story behind one of North Carolina’s most important materials.

SEAGROVE — The dirt road ends in the middle of a forest near Seagrove, North Carolina.

And at the end of the road, Ben Owen III of Ben Owen Pottery sits in the cab of a backhoe, moving the giant levers at his feet, controlling the machine’s arm and bucket. He is using the backhoe to dig clay out of a pit and pile it next to the backhoe.

Some folks watching this scene would say a hole is being dug and dirt is piling up. Others watching the scene might recognize the 'dirt' as clay. Owen looks at dirt a little differently, especially when what he is digging up is clay.

“You look at the potential for that lump of clay and what we can do with it, and that’s what makes it special,” he explains. Owen climbs out of the backhoe and picks up a piece of the clay. He starts smashing it and rolling it in his hands.

The Real Dirt About Clay“The first thing I look for is workability — is it going to be sticky and glue itself together,” explains Owen, as he shows how the clay is becoming soft and moldable. “That’s one of the first qualities because when you put it on the wheel, you want something that has workability.”

To the untrained eye clay is, well, just clay. It all looks the same. But it’s not. And before Owen can work his magic — molding, working, and firing clay into functional pieces of pottery — he must find the right type of clay. And he finds it in the Seagrove area.

“This clay must have a really good foundation, having those properties of workability and strength that will hold up to temperatures in the firing and finishing,” Owen says happily, holding his newly formed ball of clay and gesturing toward the pile of clay he has unearthed. “It also has to be durable, to be able to serve afternoon tea or just hold water for flowers. Those are the important qualities we have to look at.”

It’s not surprising that Seagrove became a center for pottery in North Carolina or that Owen’s forefathers settled here and made pottery for the European settlers. In fact you could say that Owen is carrying on a family tradition.

But why Seagrove? 

After all, clay minerals are found all over the place. However, it is not the type of clay that can be used to manufacture everything from bricks to pottery. The particular types of clay with the specific chemical makeup that allows it to be made into useful items is only found in certain regions.

Clay starts as igneous rock, which is formed when molten rock under the earth’s surface solidifies. Millions of years ago, the Piedmont area of North Carolina was very geologically active. Molten rock was close to the surface.

Over millions of years, nature broke down that igneous bedrock of the Piedmont region into fine-grained soil. And because of the gentle slope of the land, the soil weathered and settled where it was. That’s called primary clay, and it’s very pure.

The soil is changed physically and chemically during the weathering. The new soil is tightly packed and it contains the feldspar minerals, which include sodium, calcium, alumina, and silica. That rocky recipe, when mixed with water in certain proportions, is the perfect mix for pottery.

The silica hardens the clay in firing. The alumina slows the firing process enough to prevent cracking and breaking. The minerals added to the primary clay influence color, strength and heat tolerance.

Ceramic engineer Steve Blankenbeker shows the seam of primary clay in the pit that Owen dug.

“The pure clay is right here at the top of the seam,” says Blankenbeker, chopping at the clay with a pickaxe. “The first thing we look at when we find this clay is how plastic it is, how moldable it is.”

Then he shows off a clump of clay from lower in the pit. Although it looks the same, the new clump is very dry and brittle.

“Once you find clay that is plastic, the next thing you have to do is burn it, to find out the temperature at which it becomes solid,” explains Blankenbeker. “Usually, the lighter clay takes more heat so we figure out the temperature where it solidifies and then we see what color it is.”

The journey of the clay from pit to pottery is a long process. The clay is crushed, the debris removed and then turned into slurry. Once the water is removed, it is then molded and cut into workable clumps, which Owen can use to make pottery.

The clay is put on a wheel, shaped and then baked in a wood-fired oven at 2200 degrees or higher. You could call it a natural art, taking the raw material of the earth and creating a useful and beautiful product. 

“When we can make something fresh and continue that tradition of making something out of what’s in the area, that’s what is gratifying for me,” adds Owen.

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