low heat firing and mixing clay

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Gary Dickson 21 years ago

Hey All,

I am new here and new to pottery...

In June I spent 10 days in Mexico in a workshop with Juan Quezada learning his pottery method. My entire experience prior to that was 25 years ago in high school -- so I know very little about anything besides Juans method. I have since read some books in an effort to answer questions but it seems that Juan does things in a way that it pretty different than the rest of the world.

Since returning home to Washington state I have spent a lot of my spare time trying to get into doing the things Juan taught in the workshop. He finds, digs and processes his own clay -- uses a single-coil method to form the pots -- burnishes them for the shine -- paints them with human hair brushes

-- and burnishes them some more. He then fires then using cow dung as the fuel for the fire.

I have tested three different local clays and have had a couple of issues (varying degrees) with all of them -- the first being that they don¹t have much elasticity to them and they don't hold shape well. Is there something I could add to help?

Also, after firing them the surface of the pot, when rubbed, comes off in a very fine powder. Any idea what might be the cause of that? I think that either they did not fire hot enough and/or they need some sort of binder added to them. I have been firing them with the same exact process as we did at the workshop except I have been using wood for fuel because the moisture up here makes cow-pies an almost impossible source for fuel. I have fired for about 35 minutes but I am wondering if the wood fire does not get as hot as the cowpies.

Any advice would be deeply appreciated. I would prefer to use resources and processes that are as simple, primitive (and cheap) as possible.

Thanks, Gary D.

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Slgraber 21 years ago

i think part of what makes cow pies fire fast & hot is the straw component along with the nitrogen.

i suppose adding straw to your wood fire might get hotter faster?

i've never tried it but i know using fertilizer can make crude bombs but might also work in your fire. add sparingly until you agree that it works or doesn't and doesn't blow you or the pots up.

see ya

steve

steve graber

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Gary Dickson 21 years ago

I fired last night using bark and had better results -- but it's going to take a LOT of bark. So straw might be a very good option -- I'll have to give that a try! Unfortunately I didn't position the covering properly and ended up with a reduction firing :-/

Any ideas regarding what (and how much of what) I might be able to add to my clay to improve plasticity?

Thanks, Gary

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Slgraber 21 years ago

you sound like you're trying to keep your pots "pure", but having messed around with my own black fire pots i like using the basic commercial clays from my supplier. i started with soldate60, and tried "woodfire", "sculpture claybody", and porcelain. i like the porcelain results the best but do get fired cracks. one of these days i'll apply slip porcelain onto some leather pots with the stronger claybodies.

maybe blend some percent of commercial clay into your usual stuff.

i cheat all the way. i throw the pots, fire to bisque, add graphite onto the bisquepots, and fire them in a can full of saw dust. i place the can in a gas kiln and fire until the metal can glows red.

see ya

steve

steve graber

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Mud Dawg 21 years ago

You don't have to worry about the fertilizer blowing up your kiln. Explosives utilizing fertilizer as their base ingredient need a specific type of fertilizer, a binder and a kicker job. We learned how to make field expedient explosives in special forces. Steve in Tampa.

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low heat firing and mixing clay

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