Carol Tripp on sun 23 mar 03
Yikes, I mixed a glaze at the Art Centre, using a tried and tested recipe,
to which I added 2% copper carbonate, which hadn't been done before but I
figured 2% copper carb was not a radical addition. BUT, when I made the
glaze, which called for Calcium Borate Frit, there was none, only Borax
Frit. I phoned the person who usually mixes this glaze and asked her about
it and she said she always uses the Borax Frit because there is no Calcium
Borate Frit in the storeroom. (So why did she write Cal Bor Frit in the
glaze book I asked myself.) But the bell didn't ring loud enough to make me
stop and I carried on even though I harboured my doubts. It's been tried
now and it comes out all bubbly. Oh. I am leaving town on Saturday and I
would like to try to fix this glaze before I go. I don't want them all to
say mean things about me while I am gone. Just kidding. I just don't like
leaving mistakes unfixed.
TIN WHITE ^9-10 ox (called Tin Mint due to the added copper carb)
22 Potash Feldspar
17 Flint
3 Dolomite
36 Calcium Borate Frit - but Borax Frit substituted
22 Ball Clay
6% tin oxide
2% copper carbonate
My INSIGHT is on an out of order computer so I can't enter and figure this
out myself. Could someone please assist? The glaze chemicals are all from
Potclays, in England.
Thanks a million.
Best regards,
Carol
Dubai, UAE
Where a little bit of NCECA arrived in the mail courtesy of the gracious Nan
Kitchens; postcards, ribs, pamphlets etc. What a wonderful woman she is.
Usual disclaimers..., heck, I've never even met her.
_________________________________________________________________
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June Perry on sun 23 mar 03
Carol, no one can give an accurate picture with this glaze unless they have
the number and/or formula of the frits involved. There are several boron
frits on the market, many with varying amounts of calcium. For example, the
most common boron frits like Ferro 3124, 3134, 3195, all have calcium as do
others.
Have you fired a test of this glaze? It may turn out OK and not need fixing.
To fix it would take a bit of work. You would need to supply the formulas
for both the frit you used and the intended frit and the size of the batch
you made. Then the formula of both would have to be taken back to molecular
formula to see what adjustment would have to be made.
Regards,
June Perry
http://www.angelfire.com/art2/shambhalapottery/index.html
Lily Krakowski on sun 23 mar 03
Ain't it always so?
Your problem is a multiple one. It is not clear whether you used the same
frit the previous Mixer used, or a different one. Unfortunately in too many
studios things are not labeled accurately, so if she used a frit in that
particular box/bag/bin, and you used the same I would go with that.
People say "borax frit" which really is not correct, or "boral"frit which is
correct, and then Calcium Borate Frit of which there is a large family and
as Helen pointed out it could be "anything".
The copper carbonate can have affected the maturation point. Some colorants
are fluxes, some are refractory...copper is a flux. My guess is that there
is where your problem lies. I am sorry to say this,but before you go on
your trip set some of your new mix aside to dry. When you get back I would
suggest a straight line blend with the base glaze WITHOUT colorant at all,
and ANOTHER with the base glaze with 10% more clay in it. Between these two
you ought to get something that does not bubble.
And last. Get the others in your studio together and make clear explicit
labels for your supply bins....
Carol Tripp writes:
> Yikes, I mixed a glaze at the Art Centre, using a tried and tested recipe,
> to which I added 2% copper carbonate, which hadn't been done before but I
> figured 2% copper carb was not a radical addition. BUT, when I made the
> glaze, which called for Calcium Borate Frit, there was none, only Borax
> Frit. I phoned the person who usually mixes this glaze and asked her
> about
> it and she said she always uses the Borax Frit because there is no Calcium
> Borate Frit in the storeroom. (So why did she write Cal Bor Frit in the
> glaze book I asked myself.) But the bell didn't ring loud enough to make
> me
> stop and I carried on even though I harboured my doubts. It's been tried
> now and it comes out all bubbly. Oh. I am leaving town on Saturday and I
> would like to try to fix this glaze before I go. I don't want them all to
> say mean things about me while I am gone. Just kidding. I just don't
> like
> leaving mistakes unfixed.
>
> TIN WHITE ^9-10 ox (called Tin Mint due to the added copper carb)
> 22 Potash Feldspar
> 17 Flint
> 3 Dolomite
> 36 Calcium Borate Frit - but Borax Frit substituted
> 22 Ball Clay
>
> 6% tin oxide
> 2% copper carbonate
>
> My INSIGHT is on an out of order computer so I can't enter and figure this
> out myself. Could someone please assist? The glaze chemicals are all
> from
> Potclays, in England.
>
> Thanks a million.
> Best regards,
> Carol
> Dubai, UAE
> Where a little bit of NCECA arrived in the mail courtesy of the gracious
> Nan
> Kitchens; postcards, ribs, pamphlets etc. What a wonderful woman she is.
> Usual disclaimers..., heck, I've never even met her.
>
>
>
>
>
> _________________________________________________________________
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Lili Krakowski
P.O. Box #1
Constableville, N.Y.
(315) 942-5916/ 397-2389
Be of good courage....
David Hewitt on mon 24 mar 03
June Perry has commented on the problem of identifying borax frit as
this is not precise enough. There is also a problem with ball clay.
There are numerous ball clays and these can vary quite widely. I think
you need to talk to the originator of the recipe in more detail.
In message , Carol Tripp writes
>Yikes, I mixed a glaze at the Art Centre, using a tried and tested recipe,
>to which I added 2% copper carbonate, which hadn't been done before but I
>figured 2% copper carb was not a radical addition. BUT, when I made the
>glaze, which called for Calcium Borate Frit, there was none, only Borax
>Frit. I phoned the person who usually mixes this glaze and asked her about
>it and she said she always uses the Borax Frit because there is no Calcium
>Borate Frit in the storeroom. (So why did she write Cal Bor Frit in the
>glaze book I asked myself.) But the bell didn't ring loud enough to make me
>stop and I carried on even though I harboured my doubts. It's been tried
>now and it comes out all bubbly. Oh. I am leaving town on Saturday and I
>would like to try to fix this glaze before I go. I don't want them all to
>say mean things about me while I am gone. Just kidding. I just don't like
>leaving mistakes unfixed.
>
>TIN WHITE ^9-10 ox (called Tin Mint due to the added copper carb)
>22 Potash Feldspar
>17 Flint
>3 Dolomite
>36 Calcium Borate Frit - but Borax Frit substituted
>22 Ball Clay
>
>6% tin oxide
>2% copper carbonate
>
>My INSIGHT is on an out of order computer so I can't enter and figure this
>out myself. Could someone please assist? The glaze chemicals are all from
>Potclays, in England.
>
>Thanks a million.
>Best regards,
>Carol
>Dubai, UAE
>Where a little bit of NCECA arrived in the mail courtesy of the gracious Nan
>Kitchens; postcards, ribs, pamphlets etc. What a wonderful woman she is.
>Usual disclaimers..., heck, I've never even met her.
>
>
>
>
>
>_________________________________________________________________
>MSN 8 with e-mail virus protection service: 2 months FREE*
>http://join.msn.com/?page=features/virus
--
David Hewitt
David Hewitt Pottery
7 Fairfield Road, Caerleon, Newport,
South Wales, NP18 3DQ.
Tel:- +44 (0) 1633 420647
Fax:- +44 (0) 870 1617274
Web:- http://www.dhpot.demon.co.uk
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