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Systems for processing dug clay

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Hi Forum,

I am looking for pointers to good systems for processing dug clay. The clay I have looks good but to prepare any reasonable quantity takes time and effort. So before I move to preparing larger quantities I'd like to see how people do it. It will be a low-tech approach. I have read that people use tanks containing water and raw, unwashed clay which is soaked and agitated to put the clay in suspension. This clay bearing water is then run through a system of troughs and settlement pools.

I am hoping that there are some books/photos/diagrams/detailed descriptions showing what an array of of this type might look like. How and where is organic material filtered out?

If there is any way of getting gravity to help move the materials that would be good. Ways of agitating the clay which don't consume all your energy?

I have heard it said that it is better to weather and dry the clay and then crush the clay before rehydrating. But I have no idea why. And drying and crushing takes time and energy.

Any cheap mechanical aids?

I expect to be processing about a tonne of raw clay in one pass.


Thanks in advance


Andy K

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welcome, andy.

"tonne" tells me you are probably not in the USA.   i am inferring that you have tested this particular clay by mixing, making and firing it to your satisfaction.   there are several books that i have read that talk about this process.   one written by an englishman in the 1970-80 period.  i cannot remember the name of the book or the author but i know someone here mentioned it last year.  the green cover shows a teapot and the theme of the book is that you can build a lot of your own tools and save money by firing with cooking grease from local restaurants.   

i knew a potter who slaked his clay down a series of wooden troughs that had wire screening starting with large openings at the top and working down to small square wire we call ratwire.  it is used in places like under a porch to prevent animals from getting in.  

will look for the title and author.      edit     found it   The self-reliant potter by   Andrew Holden,   1986.   maybe you can find it in your local libray.

Edited by oldlady

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Hi Oldlady,

Thanks for your suggestion.  I actually live in France, miles away from any libraries. That book is available but expensive, which is a shame as it looks like it might have some interesting things in it. Perhaps I can find a soft copy on the net.

Your friend's system sounds like what I'm thinking about. If you have more details, I'd be interested. Clay is heavy. Anything you can do to avoid manhandling it too much is a good thing. I am thinking of a metal trailer which is water tight that I can fill with clay using a mechanical digger and with water. Then I need to let it soak and agitate it somehow. I can use a garden rake but it's still hard work. Then run off the water via guttering(possibly fitted with various sizes of filter) into another tank to settle. Previously I just filled a tank and agitated with a rake and then used a saucepan to transfer the clay-bearing water to a big bin through a filter( 60 mesh+panty hose) to get rid of twigs and vegetal matter. Even that was quite a lot of effort.

I have not tested the clay as I don't have a kiln yet. I was going to ask a local potter to do it for me. I imagine the testing involves biscuit firing a number of test pieces at a range of temperatures in order to see how it stands up... literally. Is there anything else I should be looking for in the tests?



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Check out Japanese videos on YouTube on processing clay, a lot of pottery villages there dig and process clay on site.  They use water powered hammers to pulverize the hard dry clay and then it is mixed with water and settled and dried.  It's a very cool traditional process that is still in use despite the invention of industrial process.

If you're looking for less labor intensive processing. Perhaps a mill, press and pugmill would be better.  Mill the hard clay into fine powder, hydrate and press the water out and finally pug the moist clay until homogenized.  

Sounds like a lot of work any way you go, for something that is so cheap and easily available already, but I understand the desire to use clay from where you live.  A good compromise would be finding a local clay supplier and purchase powdered clays from them in bulk, and mix your own.

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