Hi, I am newbie. I am currently constructing a rocket stove mass heater. I have made the burn chamber and am ready to make the riser. I was using clay that I found in a creek bed with perlite and some refractory furnace cement (Menards). The clay is a blue grey and is pretty sticky. After a lot of reading I am now doubting the clay I am using. So I am wanting to use Lincoln 60 fire clay. I haven't had much luck finding any in the Des Moines (Central Iowa area). I am wondering if anyone knows where I can purchase some or a good alternative in the Iowa area.
Has your reading included the ways to test the capability of local clay/soil? Unless you have tested it and found that it cracks too easily and has no plasticity, you can probably use it. Don't take published mix ratios as gospel, some clays already have a lot of sand or silt in them and are perfect to use as is, while the addition of sand would make them too weak.
Location: Upstate NY, zone 5
posted 4 years ago
I have built pottery kilns, which have to get to 2000+ degrees for hours on end, with local clays straight out of the ground (mixed with dried grass clippings for wet strength and insulation when fired). Even a sandy clay that was hardly workable when wet made a good kiln, durable when fired to full temperature.
Hi Tom; Keep calling around to building supply places, not the big ones but the out of the way ones. Also just ask for fireclay , lincoln 60 is very common but hawthorn is also a well known name and i'm sure there are other brands ,so don't confuse them say fireclay and see what they say. You can also look for masons in the phonebook and call and ask if they know where to get some or... maybe they have extra left over. There will be some available you just have to track it down. I have even located it at a concrete dealer ! Don't give up its out there. And as glen has said your local clay may be workable with the right mix.
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You are right to be a little hesitant to trust the type of clay you have! Usually the Blue grey stuff is an ancient pre-historic ooze very low in Alumina, and most
potters/ceramists,when they find this color out in the field discard it on sight !
However as Glenn was telling you, the tests that determine what is and is not good clay are simple direct and nearly fool proof, I am adding a link to a site I use
for the background knowledge you need to proceed, read this article and how to judge good clay, While this sights for people who want to make high temperature
kilns much of the information in these Articles has helped other Rocketeers a lot !
We got our lincoln 60 from the archie bray foundation they will freight things to you. i would check with them and they may know someone in your area or they may sell you some themselves. I would also call around to all of your local clay studios to see where they get there clay materials from and then contact there suppliers.
If no one from the future comes to stop you is it really that bad of a decision?
Big AL ; Excellent article on fireclay, Thanks for sharing !
Not all who wander are lost... J.R.R. Tolkien
posted 4 years ago
Thanks, everyone for all the help. I ended up using some refractory cement, pottery type clay, and perlite for my heat riser. Seemed to work Ok. Called around to quite a few places an no luck yet. I will keep trying and keep my eyes and ears open. Thanks again for all the help. I have learned a lot here.
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