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Re: native pottery part 2

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iowabow:
I have made a small test coil with the lime added to the clay. I am testing the shrink rate of a 10 inch coil. If it only shrinks 10 percent we should be good. My particle size is very very small and will represent a more refined pottery of the same era (Mississippian). so If you are looking for larger particle sizes then crushing the shells would produce the desired effect as long as you did not refine them too much.

Stringman:
Keep it coming Professor! I don't have anything to add, but I'm learning alot.  ;D

Scott

iowabow:
The coil is still wet but new clay seems a bit "short" it cracked and did not coil around my finger well.
I have a few choices
A. Continue with the lime into the clay and then when it reaches working consistency store it and let it age for three weeks. the aging will make the clay more plastic
B. add a vinegar to the clay to decompose the organic material
C. Add another clay body to the material that I have

My clay has a very slow dry rate. This tells me that the particle in the clay are very close together and water is having a difficult time leaving the mix. The lime should help with that but will make the clay less plastic so it seems to me that it is a balancing act here between plasticity and porous nature of the clay I have here in Iowa. At any rate it is going to take weeks before I have answers to all of my questions. 

What I should know is the shrink rate of the clay by tomorrow. Once the text piece has dried then I will fire it in a kiln here at work under controlled environment. so by Friday that experiment will be done.

Eric Krewson:
This Mississippian bowl shows no sign of shell tempering, others found with it did. They refer to this type as "sand tempered", don't know it that is true.

iowabow:
Thank you Eric for the photo! you are correct that some were tempered with sand there is a good report I read yesterday about that process. Funny thing.. the lime I have added to the test coil is so fine you would never know it was there. Your pot looks thick so it is most likely sand tempered so far as I can tell from the photo. I like the handle lip and things on the side. Do you know what they are for (the round dot looking things)?

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