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PIT the potter

Sculptural questions/bad ideas

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Hey all, 

I'm trying to achieve some very distressed/geological/raw textures in abstract sculptures. I received very little formal ceramic training,  but have several years of self teaching and throwing and pottery making experience, and do that full time now. But now I'm trying to flex some sculpture muscles, but find myself facing something totally different, as well as a shortage of information through google.

For my pottery business I make a lot of marbled pottery/agateware/swirlware, as I love just setting the foundation for great surface, and letting it do its thing. That's kind of the basis I have in mind for sculpting. After discovering Rafa Perez's work in an old Ceramics Monthly, my mind went wild thinking about making sculptures that grow and change in the kiln, and I have some ideas of where to go, but I'd like to bounce them around and maybe be clued in if these are futile/bad ideas, or advice on better methods to test.  

Rafa Perez:  www.mansfieldceramics.com/projects/rafa-perez-spain     I've seen written many times his sculptures use layers of porcelain and expanding black earthenware to create this growing bursting effect, is this done through natural overfiring of low fire clay? Or is this likely a specially made body? I tend to think of overfired earthenware as puddles of melt, yet I can see a resemblance to the bloating nature of a slightly overfired stoneware. 

Looking for growing clay also led me to another Ceramics Monthly article (https://ceramicartsnetwork.org/wp-content/uploads/2009/02/cmfeb04floating.pdf) which details mixing a specialty clay body in Japan. I've never mixed my own clay body, and don't have access to the equipment to do it super effectively, nor the regional materials he used. What I also lack is in depth understanding of clay chemistry to change what is used here into something usable. All of this being said, here are some things I've thought of that I want to try, but am afraid will do nothing, or much worse, damage something or ruin my 1 year old 'new' L&L kiln.

Specific ideas and questions I can't solve:
What are the stages of overfiring earthenware?
Adding Silicon carbide to a lowfire body and firing to cone 6, will this grow or will this melt?
Wedging lowfire and stoneware together and firing to cone 6 to try to get the lowfire to lose structural integrity and see how stoneware looks at end
What is likely to be the effect of small balls of dried crater glaze being lightly wedged into the clay body? Anything vaguely Shigaraki-esque with eruptions through body?
What are the safest/cleanest body additions for organic burnout for texture? I have my kiln in my sister's basement and want to minimize risks/smells.
How would a Earthenware slip react to overfiring, would it create an effect or just crack underlying stoneware?
What exactly is perlite used for as a body addition?

There's probably more. Any resources for other learning are much appreciated.

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Exactly how a low fire clay will respond at higher temps depends on the clay bodies being used. I once had a student make agate/swirl ware with terra cotta and cone 6 porcelain. There was no bloating, cracking, expanding, etc. It had really nice contrast and no structural issues at all. Silicon carbide will cause glazes to froth and grown, but I don't know how it will respond in a clay body. It's worth a test.

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I have used several different low-fire commercial clay bodies for decorative surface effects on work fired to cone 10 reduction in a gas kiln.  Each clay body reacts differently; some expand and others don't.  I also use raw wild clay from my ponds and uprooted trees, again each source has different effects.  My advice is to set down and make of list of the materials you think would be available for use, then obtain about a liter of each, and make tests.  First place a spoon full of each material into a bisqued test cup and fire the sample to your final temperature with your typical firing schedule. Carefully observe the outcome of the firing.  Then wedge some into your favorite clay body and repeat the test.  

A question only you can answer:  Are you trying to create ware that has the appearance of having been 'expanded' or must the ware actually 'expand' when fired?   I have seen ware that appeared to have been expanded (holes and cracks that appear to be stretch marks) but actually were created by having material 'burn out' of the clay leaving open spaces.  I have placed paper between the edges of stacked slabs to create the effects of surface cracks.  Also used rice grains to create porous surfaces.  

As a kid I played with a vermiculite which expanded when heated.  Don't know if that material is still available since it was used then as a packing material similar to today's Styrofoam peanuts.  

Your ideas are limited only by your willingness to try it.  

LT

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1 hour ago, glazenerd said:

Very interesting rabbit hole. Do you have larger pics of these pieces that I can analyze?

SiC will do absolutely nothing in a clay body @Cone 6

I use it as a control medium for testing. You can see SiC in the CM article "SSA Formulation."  April or May? 

T

I’m not sure which pieces you meant, Rafa Perez or the Floating Clay. Those are the only Floating Clay pictures I’ve found but there are several other examples of Perez’s work. I wasn’t sure if it would at cone 6  or not if the clay body was lower firing. The Floating Clay is formulated to doing some crazy growth at cone 8, with a body that I don’t have the skills to assess in terms of its non-SiC firing properties, so I thought maybe that’d be a place to start. I could fire hotter in my kiln for specific work, or change my plan altogether of course. Ha

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1 hour ago, Magnolia Mud Research said:

I have used several different low-fire commercial clay bodies for decorative surface effects on work fired to cone 10 reduction in a gas kiln.  Each clay body reacts differently; some expand and others don't.  I also use raw wild clay from my ponds and uprooted trees, again each source has different effects.  My advice is to set down and make of list of the materials you think would be available for use, then obtain about a liter of each, and make tests.  First place a spoon full of each material into a bisqued test cup and fire the sample to your final temperature with your typical firing schedule. Carefully observe the outcome of the firing.  Then wedge some into your favorite clay body and repeat the test.  

A question only you can answer:  Are you trying to create ware that has the appearance of having been 'expanded' or must the ware actually 'expand' when fired?   I have seen ware that appeared to have been expanded (holes and cracks that appear to be stretch marks) but actually were created by having material 'burn out' of the clay leaving open spaces.  I have placed paper between the edges of stacked slabs to create the effects of surface cracks.  Also used rice grains to create porous surfaces.  

As a kid I played with a vermiculite which expanded when heated.  Don't know if that material is still available since it was used then as a packing material similar to today's Styrofoam peanuts.  

Your ideas are limited only by your willingness to try it.  

LT

Are pictures of your use of clays like that easily findable? I’d love to see. Definitely going to come down to lots of tests, just hoping to get more direction/knowledge before throwing darts so blindly. 

Ideally they’d expand. I love the idea of work that is going to change form considerably in the kiln. But I do have strong interest in using burning out additives to create good texture. I’ve got the book offered in the CAD store on the way, as I struggled to find much information online about body additions.
I’m also firing in my sisters basement, so hard to do much testing with strange burning. Ha

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Pit:

one of his pieces is paper clay: the open leaf design. Some have been tooled and formed ( as LT points out.)  yes, there are ways to bloat clay. ( usually I am asked about solving bloat).  You do not need to know clay chemistry per se: you can use premix and slurry it down and make additions. Earthenware, although sold as low fire can be formulated and fired higher. You can purposely over saturate flux levels to cause slumping: which can appear bloated. He I layering, folding, and other forming techniques. Yes, there are materials that will cause bloat.: most being sulfide based.

You can fire pieces in open lidded saggars to ensure your experimental phase does not end on your shelves. Caution: you are about to go down a very deep rabbit hole- say hello to Alice. It will take much testing to perfect this look.

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