The Walden Effect: Farming, simple living, permaculture, and invention.

How to process wild clay

Wild clay

Jenn and I attended a fascinating workshop at the Dairy Barn Saturday about digging clay out of the earth and turning it into pottery. I was surprised to learn how simple it is to process wild clay...although the techniques can be quite time-consuming.

Dry clay

The first step is to collect your clay. For best results, gather clay from within twenty inches of the surface since this weathered clay will do better. You're likely to find gray clays under coal seams and red clays elsewhere. Both are good pottery clays if you live in our area.

Clay map

In fact, I was surprised to learn that southeast Ohio is the clay capital of the world! Over half the pottery made worldwide in the last one hundred years began as clay in Ohio soil.

Clay and limestone

Okay, geography lesson over. What do you do with your wild-sourced clay?

First, let it dry out thoroughly. Then break the big lumps into smaller pieces, removing pebbles and roots in the process. The most important pieces to take out are small inclusions of limestone (the paler lump on the left in the photo above) since limestone messes with the moisture content of clay and can cause explosions in the kiln.

Breaking up the clay can be done with your hands or with a hammer on the small scale. On a larger scale, you'll want to use a hammermill of some sort.

Wetting dry clay

Next, you'll have to choose whether to wet-screen or to dry-screen your clay. Wet screening is safer --- inhaling clay dust can make you very sick. But dry screening is much easier to mechanize and perform in bulk using a 20-mesh screen shaken by an off-balance motor.

We wet-screened in our workshop. First, add water...

Wild slip

Then mix with a spoon or by hand. By hand is messy but much more effective.

Milkshake consistency

Your goal is to achieve milkshake consistency, working all of the little lumps into the main mass of clay. On a medium scale, you can do this mixing in a bucket with a dry-wall mixer drill attachment a bit like this. Or just squeeze it through your fist over and over on the small scale.

As a side note, if your clay isn't very dry, it's actually much harder to moisten thoroughly. In this case, drop the clay in a bucket of water and leave it for a few days to soak up the liquid rather than trying to force water in quickly.

Screening wild clay

Now it's time to pass the wet clay through a screen to pull out the last of the rocks and roots. I found that it's easiest to press the wet slip through the sieve with my fingers.

Then put the screened clay on a board to dry somewhat (as in the photo at the top of this post) and it's ready to use in hand-building, brick-making, or thrown pottery. Our teacher suggested firing at cone 04 for most clays in our area.

How about you? Have you ever processed wild clay?

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About us: Anna Hess and Mark Hamilton spent over a decade living self-sufficiently in the mountains of Virginia before moving north to start over from scratch in the foothills of Ohio. They've experimented with permaculture, no-till gardening, trailersteading, home-based microbusinesses and much more, writing about their adventures in both blogs and books.

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Beautiful photos! Thanks so much for inspiring ideas! looking forward to learning more soon!--mom
Comment by adrianne Sun Apr 29 08:36:28 2018
I've owned a 20 acre mini farm in southern Portage county for 20 years. When I first bought the place I found piles of broken fired pottery around the place. A few years ago I had a pond on my place expanded, and found that what the backhoe brought up was a thick, light gray, very dense clay. Have you ever heard of a Commercial Pottery up this way? Several pieces were stamped with Atwater Pottery Company. Atwater is where my place is. Can you tell me anything about the pottery company or the clay? Thanks for any info.
Comment by clover5770 Mon May 7 15:12:18 2018

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