DJJ Posted July 2, 2020 Report Share Posted July 2, 2020 Hello, new member here! I’ve become very interested in clay and pottery, and I’ve been harvesting clay from my backyard in NC. We have plenty of red clay around here. I even built my own wood fire kiln. Following tutorials online I have made quite a bit of clay from the soil. But I’ve had issues with the workability of the clay. It’s either too sticky to work with or is real crackly (breaks apart easily when kneading it). I’m curious, is the moisture content wrong? Am I not letting it age enough? Why does it not have the consistently of professionally produced clay? I have run in through a strainer multiple times and dried it in a pillow case. I also added grog from an old pot. Any recommendations? Thank you! Link to comment Share on other sites More sharing options...
oldlady Posted July 2, 2020 Report Share Posted July 2, 2020 professionally processed clay contains a blend of clay types. your local clay may need something different as an ingredient to prevent the problems you mention. a couple of years ago, a potter near Albany blended her local clay. cannot remember her name but maybe you could search out some of her posts and their responses. good luck. Link to comment Share on other sites More sharing options...
liambesaw Posted July 2, 2020 Report Share Posted July 2, 2020 3 hours ago, oldlady said: professionally processed clay contains a blend of clay types. your local clay may need something different as an ingredient to prevent the problems you mention. a couple of years ago, a potter near Albany blended her local clay. cannot remember her name but maybe you could search out some of her posts and their responses. good luck. You thinking of @GreyBird? And her Hudson River clay? Link to comment Share on other sites More sharing options...
liambesaw Posted July 2, 2020 Report Share Posted July 2, 2020 5 hours ago, DJJ said: Hello, new member here! I’ve become very interested in clay and pottery, and I’ve been harvesting clay from my backyard in NC. We have plenty of red clay around here. I even built my own wood fire kiln. Following tutorials online I have made quite a bit of clay from the soil. But I’ve had issues with the workability of the clay. It’s either too sticky to work with or is real crackly (breaks apart easily when kneading it). I’m curious, is the moisture content wrong? Am I not letting it age enough? Why does it not have the consistently of professionally produced clay? I have run in through a strainer multiple times and dried it in a pillow case. I also added grog from an old pot. Any recommendations? Thank you! Some clays are plastic, some aren't. Yours doesn't sound plastic. You can try adding some ball clay or bentonite to increase plasticity. Clay is not clay is not clay if you know what I mean. Commercial clays are mined and blended, containing a mixture of primary clay, Feldspar, silica, and ball clay or bentonite. In other words, they are engineered to have specific properties such as workability, plasticity, firing temperature, vitrification, expansion. When working with clay you've dug up from your yard, you are working with secondary clays, which is the basis for earthenware. Very fine clays that are washed into place, settling in layers, and for the most part free of gravel and sand. However with all of this washing, the clay becomes contaminated with things like iron and fluxes, which lower the melting point. How this affects your clay is entirely based on location, and even in the same location, many layers of different secondary clays can be found. You could have ball clay and a high iron clay laying right on top of eachother, you never know. That would be lucky for you, since your clay lacks plasticity! So anyway, the short answer to your questions is that commercial clay is engineered for specific properties. Your clay you've harvested is lacking plasticity. You can fix that specific property by blending in small amounts of a highly plastic clay. Link to comment Share on other sites More sharing options...
DJJ Posted July 2, 2020 Author Report Share Posted July 2, 2020 I’m sure it has a lot of iron in it because it is very red. Link to comment Share on other sites More sharing options...
liambesaw Posted July 2, 2020 Report Share Posted July 2, 2020 7 minutes ago, DJJ said: I’m sure it has a lot of iron in it because it is very red. If you're set on using it, it would probably be a good idea to have a mineral assay done on it so you can determine the levels of silica, alumina, iron, calcium, potassium, sodium, etc. And then you can formulate a good plan on how to amend it. At least that's what I'd do if I were sitting on a big pile of clay. The downside may be that your back yard will not last forever as a source and will never look the same once you start digging Link to comment Share on other sites More sharing options...
DJJ Posted July 3, 2020 Author Report Share Posted July 3, 2020 I’m using a post hole digger and making small holes. Link to comment Share on other sites More sharing options...
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