daniel on sun 21 mar 04
Hi ya,
I'm going to ask one of those it depends kinda questions.
I throw stoneware mainly and groggy ones rather than gritless ones as a
rule. I have begun throwing porcelain and very much like it but I have
noticed that porcelain seems to dry more rapidly than the stonewares that
I'm used to. I realize that the everything from the weather to the phase of
the moon will influence drying rates and so as Spring is about to, I'm
seeking opinions. Have I merely been caught on the hop by an early sproing
of Spring or does porcelain really dry a bit faster than other clays ?
Thanx
Daniel
Antoinette Badenhorst on sun 21 mar 04
Yes it dries quicker. Porcelain is either thirsty or too wet to handle.
That is why it is so difficult to throw with. You have to know exactly
where you are going to prevent collapses. It trims better when dryer
though and you need sharp tools!
I was wondering about that the other day and wonder if the gurus have an
answer as to why it is like that. One can also change the shape of
porcelain when you wet it and very gently goes to work to change the
shape. My only thought is that it is because there is much less alumina
in porcelain than in other clays.
Antoinette;(struggling through "Science for the Potter" and working on
an exhibition at the same time)
Antoinette Badenhorst
105 Westwood Circle
Saltillo MS
38866
662 869 1651
www.clayandcanvas.com
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of daniel
Sent: Sunday, March 21, 2004 12:24 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Porcelain drying rate
Hi ya,
I'm going to ask one of those it depends kinda questions.
I throw stoneware mainly and groggy ones rather than gritless ones as a
rule. I have begun throwing porcelain and very much like it but I have
noticed that porcelain seems to dry more rapidly than the stonewares
that
I'm used to. I realize that the everything from the weather to the phase
of
the moon will influence drying rates and so as Spring is about to, I'm
seeking opinions. Have I merely been caught on the hop by an early
sproing
of Spring or does porcelain really dry a bit faster than other clays ?
Thanx
Daniel
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Paul Herman on sun 21 mar 04
Daniel,
The quicker drying of your porcelain is probably because of the
differences in clay body formulas.
Porcelain commonly has more non-plastic ingredients than stoneware.
Porcelain might be half clay, and half feldspar/silica. The stoneware
bodies I use are 70-80% clay, and 20-30% non-plastic ingredients. My
porcelain, 55% clay.
Regards,
Paul Herman
Great Basin Pottery
Doyle, California US
http://www.greatbasinpottery.com/
----------
>From: daniel
>To: CLAYART@LSV.CERAMICS.ORG
>Subject: Porcelain drying rate
>Date: Sat, Mar 20, 2004, 10:24 PM
>
> Hi ya,
>
> I'm going to ask one of those it depends kinda questions.
>
> I throw stoneware mainly and groggy ones rather than gritless ones as a
> rule. I have begun throwing porcelain and very much like it but I have
> noticed that porcelain seems to dry more rapidly than the stonewares that
> I'm used to. I realize that the everything from the weather to the phase of
> the moon will influence drying rates and so as Spring is about to, I'm
> seeking opinions. Have I merely been caught on the hop by an early sproing
> of Spring or does porcelain really dry a bit faster than other clays ?
>
> Thanx
> Daniel
Ivor and Olive Lewis on mon 22 mar 04
Dear Daniel,
To answer that question knowledge is needed about the proportions of
mineral fractions, not only the Silica and Felspar, but also the true
mineral nature of any clay you are adding to your clay mixture.
Best regards,
Ivor Lewis. Redhill, South Australia
.
Ron Roy on tue 23 mar 04
Hi Daniel,
Yes - porcelain takes some extra care in drying - have to baby it - dry it
slow - recompress any stretched parts like rims or they will curl.
If there is no bentonite to slow the drying it can go very fast - become a
tent maker.
If you don't slow the drying they will dry unevenly and never get back to
even again. Stoneware will even out if given the chance but not porcelain.
Get them off the bats as soon as possible and over onto the rims - paper
over slows em down just right by the way - trim when just right - the
window is narrow so watch em like a hawk.
Just like babies - don't forget about em.
RR
> I'm going to ask one of those it depends kinda questions.
>
> I throw stoneware mainly and groggy ones rather than gritless ones as a
>rule. I have begun throwing porcelain and very much like it but I have
>noticed that porcelain seems to dry more rapidly than the stonewares that
>I'm used to. I realize that the everything from the weather to the phase of
>the moon will influence drying rates and so as Spring is about to, I'm
>seeking opinions. Have I merely been caught on the hop by an early sproing
>of Spring or does porcelain really dry a bit faster than other clays ?
>Thanx
>Daniel
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
Craig Martell on tue 23 mar 04
Antoinette sez:
>My only thought is that it is because there is much less alumina
>in porcelain than in other clays.
Hi:
Actually, kaolins have more alumina than ball clays and fire clays and
since kaolins make up the major part of a porcelain body, the above comment
may not be true. The ideal percentage analysis for kaolin gives it 40%
alumina. Ball clays are about 30% and fire clays around 25%. But since
there is more clay in a stoneware body, as Paul Hermann pointed out, you
would have to figure this out for each specific body. Many ball clays are
kaolin based clays but have less alumina and more free silica etc, ad nauseum.
Another factor with drying rate is particle size. Kaolins have a larger
micron particle size than ball clays and some fire clays. The finer
particle size clays are more plastic and packed tigher so this will slow
the drying rate.
regards, Craig Martell Hopewell, Oregn
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