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Raw clay for abo pottery (build along)

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Zuma:
Hi iowabow,
Thanks
I read your link (part 2) mostly about adding burnt shell.
Not necessary for grog but for plasticity and shrinkage.
Do you think shrinkage does harm to a pot (stress or the like) ?
I wonder if my clay has enough ground limestone to do the same?
I have an extensive pottery collection. Most grog's are crushed quartz.
Some early ware with plant fiber, steatite and quite a bit of shell (mostly coastal finds) although some here on the Shenandoah use mussel shell.
zuma
edited the stress part

Jodocus:
Without having had a closer look, and with only limited experience, but I would say you do not need to filter that clay. If it comes from deep in the ground, it will not contain no debris of considerable size. Like roots or the like. Single pieces and larger rocks will also come out while wedging. Filtering is lots of work. Unless I want a super smooth surface, I dont.

I've also seen people filter the dry, crushed clay, but do this outside. Clay is easy to crush once it has frozen thoroughly and thawed again, then dried.

If you have problems with hard clay, simply soak it for a longer time. 7 to 10 days will make for soft clay usually even if it was dried completely.

for tempura, I have tried sand, crushed pottery and horse manure. The manure gives best workability and will result in porous, light, and heat tolerant pots. The sand makes for dense, heavy pottery, try out how much is good. Crushed pottery is probably ideal for many purposes, but it is so much work to crush and sieve the stuff.
I also got away with non-tempered clay more often than not.

Do dehydrate my clay, I fill it in a cotton bag (got it in hte army for the laundry) and hang it in a tree, the water will drip out within a couple of days. Professional potters seem too use plaster plates, thick, dense fabric will do as well.

Also, I would recommend processing quite a bit of clay at a time, as the process is messy and the product stores well  ;)

Zuma:
Thanks Jodocus,
Great info.
I will be looking for some tight fabric bags. Because dehydrate is
what I need to do faster. Great idea!
Since this clay came from a well being drilled, I had no idea what was in it.
The real reason for the filtering.
I had the clay in slip form in a day or two by crushing it in the water and
filtering through a sive was easy,when pouring from bucket to bucket.
Zuma

Don Case:
I used a big slab of dry plaster of paris about an inch thick. Pour about a half inch of slip on it and it sucks the water out in no time. Of course then you have to wait for the plaster to dry before you can do it again.
Don

Zuma:
 Don,
Can you just scrape the clay up off the slab and use it to build a pot with?
Plaster is very cool material. You can mold it, sculpt it, and it dries real fast. Then you can saw it, grind it or sand it. I have made plaster molds and cast objects in them from slip, silicone and latex.
Not elaborate as the split molds they use in casting large ceramic figures etc.
I would imagine making a 2 gallon plaster box or basin would be a little pricey?
But what a great tool for drying clay.
Zuma

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