John Hesselberth on sat 30 dec 00
NeilBerkowitz wrote:
>This past quarter I switched to classes at a different studio to get my
>first experience at high fire. I hadn't known that we would also be doing
>soda firings, and I had opportunity to participate in my first three soda
>firings. Seeing other people's soda or salt fired work was not new to me,
>but I wasn't prepared for how well suited soda was for my own work. I'm
>hooked--at least for now.
>
>However, since I produce mainly functional ware I would like to know how
>durable the resulting glaze is. Seems to be a basic question--perhaps too
>basic a question. But a search through several books hasn't yielded any
>answers. Apparently, durability isn't considered of sufficient
>importantance to merit a sentence or two. Any help?
>
Hi Neil,
I think the answer is that nobody knows. It probably depends on the
durability of the underlying glaze, if any. Soda, like salt does not
completly coat a pot, particularly inside corners of mugs or pitchers or
bottles.
I would certainly use stable glazes as a starter and test your work both
with the vinegar test and professional leach testing.
It is easy and inexpensive enough to test. Visit my web site at
http://www.frogpondpottery.com/glazetest.html for instructions
Regards, John
P.S. If you do test, be sure to share your results with the list so we
can all learn from it.
Also I'll be happy to work with you off-line with specific
recommendations on what/how to test. Let me know if you want help.
"The life so short, the craft so long to learn." Hippocrates, 5th cent.
B.C.
NeilBerkowitz on sat 30 dec 00
This past quarter I switched to classes at a different studio to get my =
first experience at high fire. I hadn't known that we would also be =
doing soda firings, and I had opportunity to participate in my first =
three soda firings. Seeing other people's soda or salt fired work was =
not new to me, but I wasn't prepared for how well suited soda was for my =
own work. I'm hooked--at least for now. =20
However, since I produce mainly functional ware I would like to know how =
durable the resulting glaze is. Seems to be a basic question--perhaps =
too basic a question. But a search through several books hasn't yielded =
any answers. Apparently, durability isn't considered of sufficient =
importantance to merit a sentence or two. Any help?
Neil Berkowitz
philrogers pottery on sun 31 dec 00
Kim,
I have answered this question before on Clayart. Salt glaze is perfectly
safe for functional work. There is no problem at all. Think about it - Is
there anything there that is in the least bit injurious? I can't claim
anything about glaze durability, except that Salt Glaze was used for sewer
pipes for a very long period partly because of its resistance to acid
attack, but so far as I am aware the glaze itself is harmless.
In salt glazing one is using the minimum requirements for a glaze to exist -
Silica, alumina and a flux, in this case sodium, none of which are
poisonous. If one was to use slips containing copper in conjunction with,
say for instance barium ( unlikely in a salt kiln!) then there may be cause
for concern. However, straight salt with a little Iron or cobalt, no
problem.
Phil Rogers.
Phil and Lynne Rogers,
Lower Cefn Faes,
RHAYADER.
Powys. LD6 5LT.
Tel/fax. (44) 01597 810875.
philrogers@ntlworld.com
----- Original Message -----
From: Kim Peterson
To:
Sent: Sunday, December 31, 2000 6:34 AM
Subject: Re: Soda durability
> Neil,
> I may be wrong at this, but from the lessons I've learned.. Salt fired
high
> fire is Not to be used for functional work.
> I would love to be proven wrong, since salt fired work tends to sell well
in
> Colorado.
> Kim
>
>
>
> >From: NeilBerkowitz
> >Reply-To: Ceramic Arts Discussion List
> >To: CLAYART@LSV.CERAMICS.ORG
> >Subject: Soda durability
> >Date: Sat, 30 Dec 2000 10:51:09 -0800
> >
> >This past quarter I switched to classes at a different studio to get my
> >first experience at high fire. I hadn't known that we would also be doing
> >soda firings, and I had opportunity to participate in my first three soda
> >firings. Seeing other people's soda or salt fired work was not new to
me,
> >but I wasn't prepared for how well suited soda was for my own work. I'm
> >hooked--at least for now.
> >
> >However, since I produce mainly functional ware I would like to know how
> >durable the resulting glaze is. Seems to be a basic question--perhaps
too
> >basic a question. But a search through several books hasn't yielded any
> >answers. Apparently, durability isn't considered of sufficient
> >importantance to merit a sentence or two. Any help?
> >
> >Neil Berkowitz
> >
>
>___________________________________________________________________________
___
> >Send postings to clayart@lsv.ceramics.org
> >
> >You may look at the archives for the list or change your subscription
> >settings from http://www.ceramics.org/clayart/
> >
> >Moderator of the list is Mel Jacobson who may be reached at
> >melpots@pclink.com.
>
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>
____________________________________________________________________________
__
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
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melpots@pclink.com.
>
Hank Murrow on sun 31 dec 00
Kilm wrote;
>I may be wrong at this, but from the lessons I've learned.. Salt fired high
>fire is Not to be used for functional work.
>I would love to be proven wrong, since salt fired work tends to sell well in
>Colorado.
Dear Kim;
I've been using salt-glazed pieces that I made beginning in the early
sixties with no deleterious effects. I am wondering what effects you've
observed?
Hank Murrow
Kim Peterson on sun 31 dec 00
Neil,
I may be wrong at this, but from the lessons I've learned.. Salt fired high
fire is Not to be used for functional work.
I would love to be proven wrong, since salt fired work tends to sell well in
Colorado.
Kim
>From: NeilBerkowitz
>Reply-To: Ceramic Arts Discussion List
>To: CLAYART@LSV.CERAMICS.ORG
>Subject: Soda durability
>Date: Sat, 30 Dec 2000 10:51:09 -0800
>
>This past quarter I switched to classes at a different studio to get my
>first experience at high fire. I hadn't known that we would also be doing
>soda firings, and I had opportunity to participate in my first three soda
>firings. Seeing other people's soda or salt fired work was not new to me,
>but I wasn't prepared for how well suited soda was for my own work. I'm
>hooked--at least for now.
>
>However, since I produce mainly functional ware I would like to know how
>durable the resulting glaze is. Seems to be a basic question--perhaps too
>basic a question. But a search through several books hasn't yielded any
>answers. Apparently, durability isn't considered of sufficient
>importantance to merit a sentence or two. Any help?
>
>Neil Berkowitz
>
>______________________________________________________________________________
>Send postings to clayart@lsv.ceramics.org
>
>You may look at the archives for the list or change your subscription
>settings from http://www.ceramics.org/clayart/
>
>Moderator of the list is Mel Jacobson who may be reached at
>melpots@pclink.com.
_________________________________________________________________
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iandol on mon 1 jan 01
Dear Niel Berkowitz,
Problems of durability and stability of glazes created by applying =
either particulate sodium chloride or sodium carbonate have been =
discussed several times and there should be information in Clayart =
Archives.
I have raised the question of surface crazing because of the high =
thermal coefficient of expansion of Sodium oxide; of applying the salts =
to clay which has not reached maturity so that the liquid salts which =
form on the surface of the pot are drawn into the porosity by capillary =
forces to leach out again later ( I have to take a QX3 image which =
illustrates this form of efflorescence) which can cause tainting of food =
or drink flavour; that the glaze is mechanically soft and so on.
Crazing is my favourite. I had a kiln full of Port Crocks which seeped =
wholesale over the whole surface because the clay was a degree more =
refractory than anticipated and therefore a percent or so more porous. =
If the clay has no interconnecting porosity I can accept crazing as a =
function of the Aesthetic but there will always be a problem with and =
immature clay body.
If you, or any other people wish to know more about Salt Glazing, read =
chapter twelve in Ceramic Science For The Potter by Lawrence and West or =
Use Parmellee for your first references, then go to the American =
Ceramics Societies Archives or a large reference library and follow the =
paper trail. It is an interesting journey.
All the best with your work,
Ivor Lewis. Redhill, South Australia.
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