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What Type Of Clay Is Good For Pit-Fire Bisqueing And Pit-Fire Coloring?


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#1 Spart248

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Posted 15 July 2013 - 05:48 PM

            I am planning on doing alot of pottery (thrown-ware) pit firings over the summer. However, I have nowhere to bisque the pots I throw in a kiln, so I plan to bisque-fire them in a pit fire, just as the natives did. I also plan on pit firing them again using chemical, salt, etc. to color them. What kind of clay would be best for this? In terms of both survival (not breaking from thermal shock) and receiving the coloring from the second pit firing best. Keep in mind when I say "pit firing" I don't mean "wood-firing" in a special wood fire anagama kiln or anything. I literally mean firing in a pit. I know how to pit-fire to bisque and then to pit fire for coloration.
           I have to order from this supplier, Ceramic Supply Inc. I am thinking of ordering some this S105G, white stoneware with grog. Also some S239 raku clay (without kyanite because it is cheaper). Should I spend the extra money on the raku with kyanite to increase survival? It does have a lower temp-bisque which would be easier to achieve. Do you think the stoneware with grog will have a decent survival rate with pit-fire bisquing? Or should I just solely get the raku? I imagine the only options would either be a low-fire or raku clay. If you see anything you think would fair better on their website, please let me know.

 


 

Thanks everybody :)



#2 Marcia Selsor

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Posted 16 July 2013 - 05:49 AM

I have used locally dug clay, cleaned and screened. Non-groggy terra cotta or earthenware will work.I usually bisque after burnishing.

If you add any aggregates to help avoid thermal shock, they should be fine so the burnishing won't scratch the surface.

ex. molochite.

I let the pots preheat along the edge of the pit as the fire builds up coals, then place the pots upside down on a grate..like an old refrigerator shelf or bbq grill. Then cover with sawdust and dried cow pies. Let the fire burn up to the outer surface...usually takes several hours.

Cover with metal roofing or metal sheets to avoid drafts if you are after rich blacks.

 

 

Marcia






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