Wild clay issues

[weberworks]

Hello! I have been working with wild clay from the shores of Lake Superior on and off for about a year, and have a few questions.

First, I've been using the wet processing method and can never get the clay to settle properly.  I've used vinegar to hopefully flocculate the clay and get rid of some of the lime present but it hasn't worked. When I attempted this I used about 3 quarts of food grade vinegar in roughly 60 pounds of clay done in a 5 gallon bucket, and there was clear water for about an inch from the surface. After this inch there was a distinct change to suspended clay particles. Would I benefit from adding more vinegar or another flocculant like Epsom salt, or maybe try dumping off all of the clay laden water to a certain point anyways?

Second, I have been looking to get a mineral analysis of the clay body to see the quartz and feldspar concentration, as well as looking for other things like lime, iron, copper, lead, etc. Is this just superfluous information or genuinely useful? At the moment I don't know what the clay fires to, I just know that it doesn't vitrify by cone 05 and melts at cone 6

Third, I've noticed that the clay cracks quite readily when working the clay by hand. What is the easiest way to fix this?

Attached is an image of the clay I've processed so far.

[weberworks]

Here is a decent amount of the clay, dried and ground

[glazenerd]

Questions;  heavy vegetation around the site it was collected? Does it feel sticky or tacky? Was it collected from a water shed area? Any dark/black material visible? Strong mold/bacteria odor?   Calcium (lime) is a strong natural deflocculant. However, suspect more going on than that. 

Tom

[Kelly in AK]

Very cool! I find using locally available clay both deeply rewarding and challenging. Since I don’t have issues with lime or calcium (That I’m aware of, haha!) I can’t speak to that. My clay is probably very different from yours. I have some thoughts that may be relevant though.

The first is, I wonder what you’re expecting of the clay in terms of “settling out properly.” I too use a wet or slip process to make what I collect useable. When I get the water/clay ratio how I want, it mixes in the bucket as a whole circulating vortex. It’s fluid. Not necessarily watery, but it flows enough that I’m not working any harder than I have to with the mixer. I may have understood this bit wrong, but there’s no way I could fit 60 pounds of clay and all the water in a five gallon bucket. After I get it mixed it has to go through a sieve, it’s got to be fluid. I think 20 pounds of clay is about all I could fit in a five gallon bucket full of water. Maybe. Long way to say, perhaps you’re not using enough water for it to settle out, no matter how long you wait.

The next thought goes back to flocculation. For a while I flocculated my clay with epsom salts to improve plasticity. It went from pourable to pudding state instantly. So I can’t say about vinegar specifically, but about flocculation generally, I wouldn’t expect flocculated clay to settle. It’s the very reason I flocculate my glazes, to keep them from settling. If I wanted clay to settle out that would be the last thing I did. (It was, literally, the last thing I did before clay went into drying trays, after letting it settle a couple weeks then siphoning off the water).

I could ramble on… I’ll just finish by saying don’t underestimate the potential information you can find through observation, record keeping, and testing. You will discover new things as you run the clay through the kiln, there’s a trove of data there. Many sound conclusions about the chemical composition of your clay can be made through testing you can do personally.

Good luck, and hoping to hear more about how things unfold.