Vince Pitelka on thu 6 mar 03
> So my thought was that this low fire body(dare not say the p word),
> would give me more strength in my pots than my current earthenware
> terracotta body. I guess that would not be so? It would not vitrify at
> 04 so I shouldn't bother?
> What I was hoping that these 04 bodies could give the durability and
> water tightness I can't get in earthenware.
Joanna -
Many people fire terracotta functional bodies to cone 1 or cone 2 in order
to get something approaching vitrification. Given the right body, you can
get very durable wares at that temperature without any slumping or bloating.
Trying to achieve vitrification at true lowfire temperatures by adding
glassy frit is never going to give you durable functional wares. A
terracotta body fired to cone 1 will be far stronger.
Good luck -
- Vince
Vince Pitelka
Appalachian Center for Craft
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
Home - vpitelka@dtccom.net
615/597-5376
Office - wpitelka@tntech.edu
615/597-6801 x111, FAX 615/597-6803
http://iweb.tntech.edu/wpitelka/
Joanna Jorgensen on thu 6 mar 03
Ok, Ok
So my thought was that this low fire body(dare not say the p word),
would give me more strength in my pots than my current earthenware
terracotta body. I guess that would not be so? It would not vitrify at
04 so I shouldn't bother?
What I was hoping that these 04 bodies could give the durability and
water tightness I can't get in earthenware.
I did a test with my current 04 body, to 02 and I get a nice ring. I do
not have the facilities to fire higher and its still not water
tight,though. My main source to fire large pieces is the Community
School kiln which only gets fired to 04, as mine at home is a wee little
thing.
Should I test these bodies anyway? Or is it a wasted effort for what I
am looking for?
Joanna Jorgensen
Coconut Creek, Fl
www.JorgensenPottery.com
Snail Scott on fri 7 mar 03
At 01:57 PM 3/6/03 -0500, you wrote:
>What I was hoping that these 04 bodies could give the durability and
>water tightness I can't get in earthenware.
In general, there is a trade-off at low temperatures.
You can certainly make a clay that vitrifies at ^04,
but it will need to be high in frits or cullet glass
or some such to achieve melt. This usually means very
low plasticity, better suited to casting or molding
than to throwing or handbuilding. Such clays also have
a low resistance to slumping and warping, and have an
extreme sensitivity to precise firing temperatures.
Not much margin for variation - a little past the
mark, and flop! Still, depending on the work you want
to do, it may be a viable material for you.
-Snail
Longtin, Jeff on fri 7 mar 03
Joanna,
Some thoughts: There are certain clay bodies out there that have kaolin, or
china clay, in them and possibly vitrify at ^04. The only problem is that
they have alot of non-clay elements (I do believe) that help them do that.
These non-clay elements make them extremely hard to use. Additionally, as
the bodies are more non-clay than clay the point at which they remain
stable, i.e. structurally, and the point at which the become a viteous blob
on your kiln shelf are very very close (if I recall).
If you are lucky enough to succeed at finding that point between
vitrifacation and true meltdown you will be a better potter than I, however,
you will also have pots that are not so much durable as they are brittle and
very glass-like in their feel.
This aspect will solve your absorbtion concern but will create additional
for you as regards glaze fit.
Good Luck
Jeff Longtin
-----Original Message-----
From: Joanna Jorgensen [mailto:joanna@IWANTCOMPHAX.COM]
Sent: Thursday, March 06, 2003 12:58 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: 04 porcelain
Ok, Ok
So my thought was that this low fire body(dare not say the p word),
would give me more strength in my pots than my current earthenware
terracotta body. I guess that would not be so? It would not vitrify at
04 so I shouldn't bother?
What I was hoping that these 04 bodies could give the durability and
water tightness I can't get in earthenware.
I did a test with my current 04 body, to 02 and I get a nice ring. I do
not have the facilities to fire higher and its still not water
tight,though. My main source to fire large pieces is the Community
School kiln which only gets fired to 04, as mine at home is a wee little
thing.
Should I test these bodies anyway? Or is it a wasted effort for what I
am looking for?
Joanna Jorgensen
Coconut Creek, Fl
www.JorgensenPottery.com
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Vince Pitelka on fri 7 mar 03
> You can certainly make a clay that vitrifies at ^04,
> but it will need to be high in frits or cullet glass
> or some such to achieve melt. This usually means very
> low plasticity, better suited to casting or molding
> than to throwing or handbuilding. Such clays also have
> a low resistance to slumping and warping, and have an
> extreme sensitivity to precise firing temperatures.
Snail makes very good points about low-fire "soft-paste porcelain"
claybodies. In addition, they tend to be rather brittle, and thus
inappropriate for functional wares.
Best wishes -
- Vince
Vince Pitelka
Appalachian Center for Craft
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
Home - vpitelka@dtccom.net
615/597-5376
Office - wpitelka@tntech.edu
615/597-6801 x111, FAX 615/597-6803
http://iweb.tntech.edu/wpitelka/
Pat Southwood on mon 10 mar 03
Hi,
My local supplier sells a clay called "semi-porcelanious earthenware" It
sounds like what some of you may be using.
Its not a very elegant name though!
Pat.
pat@southwood4.fsnet.co.uk
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