CINDI ANDERSON on sat 20 jan 01
Hi
Can't find anything about foaming glazes in the archives, although I
seem to
remember it being discussed at some point in the last few years.
Any input at to why glazes foam and how to fix it?
Thanks
Cindi
Martin Howard on mon 22 jan 01
There was something about this when we discussed SiC, Silicon Carbide and
its reaction with glazes if you added too much, as I did :-(
Martin Howard
Webb's Cottage Pottery
Woolpits Road, Great Saling
BRAINTREE, Essex CM7 5DZ
England
martin@webbscottage.co.uk
Paul Lewing on mon 22 jan 01
Cindi,
I don't know why glazes foam- I've always assumed it was something
soluble in one of the ingredients that had some property like soap.
Maybe one of your materials is contaminated with soapstone (that's a
joke- soapstone wouldn't do that).
I have a batch of spodumene that has always done this- had it for many
years. I've found two solutions. You can calcine the material. Or you
can do what I do- make the recipe up with lots of water a few days ahead
of when you'll need it, let it settle, and decant the water off. Do
this two or three times and it will no longer foam.. Doesn't seem tø
affect the fired glaze.
Paul Lewing, Seattle
Marni Turkel on tue 23 jan 01
Cindi
I have had trouble with glazes foaming that use spodumene. But it is not
all spodumenes, it is only certain sources of spodumene. If your glaze does
contain spodumene, see if you can find a different batch or source (some
are visually very different). I have tried washing the spodumene or
decanting the extra water from the glaze batch as Paul Lewing described,
but in the end finding a spodumene that didn't foam at all made me much
happier.
Marni
Marni Turkel
Stony Point Ceramic Design
2080 Llano Rd 1B
Santa Rosa, CA 95407
Phone: 707-579-5567
Fax: 707-579-1116
http://www.marniturkel.com
Paul Brinkmann on tue 23 jan 01
Cindi,
I don"t know why glazes foam either, but before Christmas, decided to
handbuild two gingerbread housed. I knew there was a commercial glaze that
one could use for snow. Purchased several jars of Ceramichrome, specialty
glaze #600 ,called Winter Snow. On the back lable, theres a note: Do not
spray, contains Crystalline Silica. This may be a clue. PGBrinkmann. San
Antonio, Tx.
John Hesselberth on tue 23 jan 01
CINDI ANDERSON wrote:
>Hi
>Can't find anything about foaming glazes in the archives, although I
>seem to
>remember it being discussed at some point in the last few years.
>
>Any input at to why glazes foam and how to fix it?
Hi Cindi,
Are you meaning the slurry foaming in the bucket or the glaze foaming
during firing??
Regards, John
"The life so short, the craft so long to learn." Hippocrates, 5th cent.
B.C.
Cindy Strnad on tue 23 jan 01
Cindi,
I've had glazes foam, too. They were always glazes that contained gerstley
borate. I wonder if it might be the solubles. As someone else mentioned, you
can eliminate the foaming by removing excess water and replacing it with
fresh water. If you do this several times, it will reduce and eventually
eliminate the foaming problem. BTW, if you have glazed pots and they show
surface imperfections from the foaming, rub over them with your finger to
smooth the surface before firing. It may smooth out on its own, but
sometimes it doesn't.
Cindy Strnad
Earthen Vessels Pottery
RR 1, Box 51
Custer, SD 57730
USA
earthenv@gwtc.net
http://www.earthenvesselssd.com
Earl Brunner on wed 24 jan 01
If you can tell me where I can get some of that grayish foaming
spodumene I would trade gerstley borate for it (or money).
I used to have a glaze that I really liked that used it and it has never
been the same with the other spodumenes.
Marni Turkel wrote:
> Cindi
>
> I have had trouble with glazes foaming that use spodumene. But it is not
> all spodumenes, it is only certain sources of spodumene. If your glaze does
> contain spodumene, see if you can find a different batch or source (some
> are visually very different). I have tried washing the spodumene or
> decanting the extra water from the glaze batch as Paul Lewing described,
> but in the end finding a spodumene that didn't foam at all made me much
> happier.
>
> Marni
>
> Marni Turkel
> Stony Point Ceramic Design
> 2080 Llano Rd 1B
> Santa Rosa, CA 95407
>
> Phone: 707-579-5567
> Fax: 707-579-1116
> http://www.marniturkel.com
>
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Earl Brunner
http://coyote.accessnv.com/bruec
mailto:bruec@anv.net
Janet Kaiser on wed 24 jan 01
You all know how non-existent my chemistry
knowledge is...
But surely the foaming when mixing a glaze from
dry ingredients, is the carbon dioxide being
released? Through chemical reaction? Especially
in acidic mixes pH 8 and higher? Probably
releasing oxygen laid down in some primeval
past?
Please don't tell me I have been wrong all these
years... I find it a most romantic thought!
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
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