Cleaning the native clay.

Cleaning Native Clay for Nature Art and Forest Folk

We had a major landslide a few years ago out here at Wild Ozark. It took out a vital portion of our driveway, but it gave some things in return. The earth is still moving, so the removing of that earth is a continuous process. This year I found a pretty incredible fossil and then Rob found several large deposits of native clay.

Native Clay and a Big Fossil

Perhaps that isn’t enough to pay for the damage to the driveway, but Nature did seem to recompense with a currency that made at least me happy. I love finding fossils, and I was excited about the clay. Neither of these might have been discovered without a good sized chunk of land moving aside to expose them.

Anyway, I finally got around to experimenting with the clay and the fossil is finally decorating a nightstand in one of our bedrooms after collecting dust on top of various out of the way spots for the past six months.

Part of a Lepidodendron tree from about 300 million years ago. Found in the same area as the native clay deposit.
Part of a Lepidodendron tree from about 300 million years ago. Found in the same area as the native clay deposit.

Cleaning Native Clay

I did a bit of browsing around the internet to see what I could find about cleaning native clay. Here’s one of the articles that has a video on how to clean it. I did mine a little differently, because I didn’t want to wait for the clay to dry and then crush it and then filter it.

Clay straight from the ground has a lot of non-clay stuff in it. Although this deposit was mostly clay and relatively free of sticks and trash, it still had a few rocks and some sand. There’s a good bit of shale in the area where it was found, too. Not sure if that’s still a “rock” or not, but it needed to come out of the clay.

Here’s the big hunk of native clay Rob brought me once he saw he’d uncovered it. When he saw it in the bucketload of earth he’d moved from the landslide, he came back to the house and asked me if I wanted it. He could have saved himself the trip by assuming that of course I did.

Raw native clay. It's in a large black plastic tub. Not sure of the size, but it's a lot of clay.
Raw native clay. It’s in a large black plastic tub. Not sure of the size, but it’s a lot of clay.

Skipping Steps

Rather than drying it first, I went directly to the making a slurry of it.  It didn’t all go into the water. This is why the ones in the know recommend drying and crushing it first.

After I’d gotten all I could of it to go into solution, I began putting it through a coarse sieve using the kitchen strainer.  That was not as easy as I thought it would be. It took a lot of pushing with a plastic rice paddle to get the clay that didn’t ‘water up’ through the holes.

Cleaning the native clay.

My modification still worked, but it might have been easier had I crushed and sieved first. Not sure if you’ve ever pushed wet sticky clay through a screen before, but it does tend to resist the task. I had the entire kitchen a mess before I was through.

Finally after much pushing and slopping around the wet clay and rinsing with the water (use the same water and two pots, so all of the clay stays in the pot below), all I was left with were the rocks.

The rocks left behind.
The rocks left behind.

Strain it More

So now it has to be screened for sand. Too much sand will make the clay crack and break when bending it, but not enough causes other problems. I’m not a clay expert and neither am I a potter used to using store bought finished clay, so I don’t know all the details of how this works.

I started reading to get better informed, but the information overload made me feel like I’d never learn enough quickly enough, so I decided to go with my usual way of doing things by trial and error with enough information to be a little guidance.

Getting the Water Out

Once all the clay was put through yet a finer screen (I used the splatter screen for the kitchen – and ruined it), it was now a liquid slurry. The sand that made it through the splatter screen was small and I hoped it wouldn’t cause too much issue.

The next step was to filter out the water. That is not a quick step.

Pour the slurry into a pillowcase you don't mind losing to your art.
Pour the slurry into a pillowcase you don’t mind losing to your art.

It took more than a week for the water to drip through and dry out the clay enough to remove it from inside. I put that in a gallon sized plastic bag.

I poured off the water in the bucket and returned the really fine clay at the bottom of the pot to the hardened but not yet dry clay. It was enough liquid to make the clay from the pillowcase able to knead and mix it all back together again the next morning. I did that while it was still in the Ziploc bag so it wasn’t messy.

Making Test Pieces

I made a small ball, the size I’ll want to use for my Forest Folk heads. And I also made a snake and coiled it into a circle. Both worked really well without cracking at all.

Test of freshly cleaned native clay.

Left it out to dry overnight and then burnished both pieces a little with the back of a spoon. It shined up nicely!

Burnished by rubbing the almost dried pieces with the back of a spoon.
Burnished by rubbing the almost dried pieces with the back of a spoon.

Dry It Some More

The clay has to be completely dry before I try firing it. I’m going to put it in the woodstove and see how it turns out. For the crafts and art I have in mind, I don’t really need to fire it at all. But even a little firing will make the clay more durable and might bring out different colors in it, making a more earthy tone to the art.

Test pieces drying on the wood stove.
Test pieces drying on the wood stove.

Waiting for Results?

I’ll update this post with pictures of the final outcome in a few days! Have you ever used native clay?

Here’s the post that gives the results. Short story is that I put those pieces in the stove before they were fully dry. Explosive noises ensued. Couldn’t even find a trace of them once it was all over!

But I made more and this time let them dry completely, plus started with a cold stove and built the fire over them, and those turned out incredible!

The second set of test pieces - they survived!
The second set of test pieces – they survived! The left was burnished, the right was not. The one at the top of the image hasn’t been fired yet. I had them in a cast iron skillet with aluminum foil to keep the pieces in there if they exploded. Once I got them red hot, I dropped them into a pitcher of water. No cracking at all. I was thoroughly impressed and can’t wait to do more with this clay.