Samuel Holder on sat 27 mar 99
I want to do some sculptures and fountains for outside. I'm having a
problem finding any literature or recipes for a freeze-thaw-resistant
clay body. Can your help me?
I'm already familiar with testing for porosity of a clay body.
I'm working at ^5 and ^6. Is there a frit or another material that
can be mixed into a clay body that will fill and seal the interstitial
spaces without causing the structure to slump?? Do you have (or know
of a source of) a recipe that can be used for these circumstances?
Should I be working at another cone^ temperature?
Thanks,
Samuel Holder.
Linda Blossom on sun 28 mar 99
Val Cushing's handbook has a good section on just this topic. It basically
says that you need to use a stoneware body with a pore structure that allows
water to escape rather than a vitreous body. He gives the formula to test
the clay for the correct ratio of soaked to boiled percentages. Someone
posted the number to call to order the handbook a while back. The procedure
is: make several tiles. after firing, immediately weigh them before they
take on atmospheric water. Soak them for 24 hours, dry and weigh again.
This A the soaked weight. Now boil them for two hours and then dry and
weigh them again. I find that if you take them out of the hot water and try
to weigh them they will lose weight quickly because the water is evaporating
very quickly due to the heat. I add cold water until I can handle the
tiles, dry them quickly and weigh them. This is B the boiled weight. Now
divide A by B and you get C. If this number is under .78 the body is ok. I
find grog an essential ingredient in the clay so that it is not too tight.
This pore structure is not the same as porosity as we think of it in an
underfired body. For example, when you bisque a tile, then glaze it, the
tile is extremely absorbent. However, if you were to fire it to maturity,
you would have trouble getting it to absorb the glaze. This is not a matter
of space between unfused particles due to underfiring, it is a pore system
that exists after the piece is fired to maturity.
Linda Blossom
2366 Slaterville Rd
Ithaca, NY 14850
607-539-7912
blossom@twcny.rr.com
-----Original Message-----
From: Samuel Holder
To: CLAYART@LSV.UKY.EDU
Date: Saturday, March 27, 1999 9:35 AM
Subject: Freeze - Thaw Resistant Clay Body
>----------------------------Original message----------------------------
> I want to do some sculptures and fountains for outside. I'm having a
> problem finding any literature or recipes for a freeze-thaw-resistant
> clay body. Can your help me?
>
> I'm already familiar with testing for porosity of a clay body.
>
> I'm working at ^5 and ^6. Is there a frit or another material that
> can be mixed into a clay body that will fill and seal the interstitial
> spaces without causing the structure to slump?? Do you have (or know
> of a source of) a recipe that can be used for these circumstances?
> Should I be working at another cone^ temperature?
>
> Thanks,
> Samuel Holder.
>
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