vince pitelka on fri 23 feb 01
> with respect to you formidable knowledge and with further
> respect to you , I regretfully type this .
> Fortunately , I saw this letter before I sent out congratulations to
> Bret Hinsch and his excellent information.
Khaimraj -
Well . . . . . . I guess I stuck my own neck out a bit on this one.
Occasionally someone posts something so completely ridiculous as to be
obvious, and this certainly seemed like one of them. The experimentation
with "burning glasses" sounds fascinating, and I will certianly read more
about this. But it seems apparent that the burning glasses were used for
experimentation, and not for firing porcelain wares. I am a little baffled
as to why they were even using the burning glasses, when they already had
stoneware kilns fully capable of firing true porcelain. Strange.
Best wishes -
- Vince
Vince Pitelka
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
Home - vpitelka@dtccom.net
615/597-5376
Work - wpitelka@tntech.edu
615/597-6801 ext. 111, fax 615/597-6803
http://www.craftcenter.tntech.edu/
Khaimraj Seepersad on sat 24 feb 01
Hello to All ,
Vince ,
from time to time , I run across things from the near and extreme
past , which makes me just go - huh !
I often keep these discoveries to myself lest men in white coats
appear and drag me off.
As to Porcelain , is not the premium grade stuff fired at above
1280 deg.c , Robert Fournier in his book has it listed as -
True or Hard-Paste Porcelain - firing to 1350 deg.c and
Norton - Ceramics for the Artist has the temperature listed at
1450 deg.c [ cone 16 ] .
Places listed as making this Hard -Paste Porcelain -
Limoge , Sevres .
The 1280 stuff is actually called shhh - White Stoneware.
True Porcelain is Kaolin and Silica with a little flux.
[ See Fournier - Illustrated Dictionary of Practical Pottery - for
the full story ].
This is much akin to the quiet entries I have made on ClayArt
with regards to Terra Sigillata - which is really Attic Ware
related . A fine slip being oxidised , reduced and then
oxidised again.
The confusion seems to start with Daniel Rhodes - Clay and
Glazes for the Potter .
Where he first lists the correct condition for making Terra Sigillata
then wonders off into Burnished slips.
Terra Sigillata cannot be scratched by a razor blade and is a
glass , fluxed by black iron oxide and fine particle size.
There is no mention of having to Burnish to get a gloss .
Another Huh Moment .
There is also Red Gloss Ware and Plumbate slip.
[ see - Ceramics for the Archaeologists - Shepard - pgs.180 to 181]
Mysteries in Pottery ,
Khaimraj
-----Original Message-----
From: vince pitelka
To: CLAYART@LSV.CERAMICS.ORG
Date: 23 February 2001 19:38
Subject: Re: Firing porcelain with solar lenses
>> with respect to you formidable knowledge and with further
>> respect to you , I regretfully type this .
>> Fortunately , I saw this letter before I sent out congratulations to
>> Bret Hinsch and his excellent information.
>
>Khaimraj -
>Well . . . . . . I guess I stuck my own neck out a bit on this one.
>Occasionally someone posts something so completely ridiculous as to be
>obvious, and this certainly seemed like one of them. The experimentation
>with "burning glasses" sounds fascinating, and I will certianly read more
>about this. But it seems apparent that the burning glasses were used for
>experimentation, and not for firing porcelain wares. I am a little baffled
>as to why they were even using the burning glasses, when they already had
>stoneware kilns fully capable of firing true porcelain. Strange.
>Best wishes -
>- Vince
>
>Vince Pitelka
>Appalachian Center for Crafts
>Tennessee Technological University
>1560 Craft Center Drive, Smithville TN 37166
>Home - vpitelka@dtccom.net
>615/597-5376
>Work - wpitelka@tntech.edu
>615/597-6801 ext. 111, fax 615/597-6803
>http://www.craftcenter.tntech.edu/
Janet Kaiser on sun 25 feb 01
Vince
Everyone is forgetting they were alchemists (not
potters) and were working on making gold from
base metals and other materials. Seeking the
Philosopher's Stone and all that...
Seems to me that the *smelting* power of lenses
combined with the on/off function they provided
versus a kiln or other heatsource, would be seen
as a vital breakthrough in their search. They
also made possible intense heating from above or
any angle other than beneath (brazier) or all
around (kiln) for the first time. I think they
would be used more like a blow-torch or Bunsen
burner, which were not used until after the
introduction of gas in the 19th. century.
After all, the discovery of European porcelain
was serendipity or a happy accident and not the
raison d'être of their experiments.
Janet Kaiser
The Chapel of Art . Capel Celfyddyd
HOME OF THE INTERNATIONAL POTTERS' PATH
Criccieth LL52 0EA, GB-Wales Tel: (01766) 523570
E-mail: postbox@the-coa.org.uk
WEBSITE: http://www.the-coa.org.uk
> I am a little baffled
> as to why they were even using the burning
glasses, when they already had
> stoneware kilns fully capable of firing true
porcelain. Strange.
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