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Non-Plastic Clay


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#1 yarddog

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Posted 16 April 2014 - 12:42 PM

First, a quick but heartfelt thanks to the pros among you who have helped me in the past. No mistake, I've found, is too obvious to avoid...

Now an issue with a clay body. I have two hundred and some pounds of a clay body that is barely okay for throwing, if I work fast, but seems to lack the plasticity needed for decent pulled handles. It cracks badly, and I've ruined more than a few mugs. My technique hasn't changed, and the same kind of handles with a different clay body work just fine.

This batch is from Laguna (actually, they both are) and they have been pretty consistent for me in the past.

What's the cure? Will it improve with time? Something quicker?

#2 Marcia Selsor

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Posted 16 April 2014 - 01:06 PM

I worked with the short clay in Uzbekistan. It cracked as you described. The locals added fiber from cat tails or cat tail fuzz to make handles. They wedged it in.  It worked. 

It help bind the clay. It was an earthenware.

 

Marcia



#3 perkolator

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Posted 16 April 2014 - 01:06 PM

Same clay bodys?  I'd think a commercial clay body would come pre-aged, so it's likely not going to improve much with time.  You may have to alter your technique as you would when working with something like a raku body vs porcelain.  I have never tried it, but some people have success by adding things to their throwing water - stuff like epsom salt solution, vinegar, magic water, gums, bentonites, etc etc so the material is slightly easier to work with.  If it ultimately doesn't work out for throwing, you could always use this clay body for hand building since plasticity is usually less important with these techniques.



#4 Stellaria

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Posted 16 April 2014 - 01:18 PM

Is it generally accepted that if you buy a batch of unworkable clay, that is your responsibility to fix it? Or should you call the manufacturer to see if anyone else has had a problem with it, and to see if it can be replaced?

#5 neilestrick

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Posted 16 April 2014 - 01:26 PM

So you've used this particular clay body before without problem? If so, then you might have received a bad batch that didn't get mixed properly. Or, is this batch wetter or stiffer than in the past?


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#6 yarddog

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Posted 16 April 2014 - 01:44 PM

Is it generally accepted that if you buy a batch of unworkable clay, that is your responsibility to fix it? Or should you call the manufacturer to see if anyone else has had a problem with it, and to see if it can be replaced?


The Laguna distributor is a pretty good haul from here, and I may well return it on my next trip over. But that's a couple months from now...
Meantime, I should have been more specific. The clays are Laguna 60 and 90. I love the 90, and it throws like a dream, but folks seem to want to buy mostly the more dramatic 60, so I'd like to figure out a way to use it.
And no, it's not particularly wetter or drier.
Last, is it likely that pugging a bit of 90 into the 60, say half n half, would improve the 60 or spoil both?
Thanks.

#7 neilestrick

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Posted 16 April 2014 - 02:02 PM

Usually when you blend clay bodies you get something pretty decent. Maybe just wedge together a couple pounds of each to test.


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#8 JBaymore

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Posted 17 April 2014 - 07:03 AM

I don't know those 60 and 90 clay bodies... but do they haappen to be cone 5-6 bodies? If so... do the batch dates on the boxes show that the clay is quite OLD? If so... could be the standard issue with many cone 6 bodies containing Neph Sy instead of feldspar (used at higher temps),...... the soluble soda from the neph sy affecting the water chemistry with age.

 

best,

 

.......................john


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#9 Biglou13

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Posted 17 April 2014 - 08:11 AM

JOHN

 

Are you saying that clays high in nephsy, feldspar   have limited storge time.  

I may not want to stock my cave to deep if that is the case


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#10 JBaymore

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Posted 17 April 2014 - 08:19 AM

Biglou,

 

Not for feldspar...... but yes... for neph sy.  And (like everything in ceramics) it is not ALWAYS...... becasue the Ph of the water used to mix the clay affects this, as does other components in the particualr body formulation..... and if dealing with reclaim.... the local used water that gets into the clay in use/reclaiming.

 

best,

 

.......................john


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