Lesley Anton on fri 13 jul 07
Hi all,
I am having a problem with a matte glaze that has, so far, not given
me a problem.
This is a Butter colored, matte glaze, that is very smooth usually.
I had trouble getting it to be matte in my fiber lined gas kiln but
with a slow firing down in the cooling I have had great results.
Recently, the firings have produced these crazy bubbles all over the
surface. It seems like they are where the glaze is the thickest, but
not always. These bubbles are tiny, surface bubbles, it isn't in the
clay. I wondered if anyone had any run in with this before. It
wasn't happening before but mostly on these larger pots that I have
to pour on the glaze. Is there a way to get rid of these in a re-
fire? Maybe by holding the temp at cone 10 for a bit? or slow cooling
for the first few hours only?
any advise would be so helpful
Thanks
Lesley
Lesley Anton Handmade Ceramic Lighting
323.934.3463
www.lesleyanton.com
Michael Wendt on sat 14 jul 07
Lesley,
You might try an experiment:
Make tiles of various thicknesses
and apply the glaze to these in the
approximately same manner as
the large pieces.
If the thicker tiles also do this
bubbling, it may be caused by
delayed gas escape.
As strange as this sounds, a clean
hot bisque firing with plenty of
oxygen to burn out organics
can reduce many such problems.
It follows then that a bisque-like
early firing might also solve the
problem.
Fire slowly in strong oxidation in
the early stages of firing before
the glazes begin to melt to allow
outgassing.
I hope this helps.
Regards,
Michael Wendt
Wendt Pottery
2729 Clearwater Ave
Lewiston, ID 83501
USA
208-746-3724
http://www.wendtpottery.com
wendtpot@lewiston.com
Lesley wrote:'
Hi all,
I am having a problem with a matte glaze that has, so
far, not given
me a problem.
This is a Butter colored, matte glaze, that is very
smooth usually.
I had trouble getting it to be matte in my fiber lined
gas kiln but
with a slow firing down in the cooling I have had great
results.
Recently, the firings have produced these crazy bubbles
all over the
surface. It seems like they are where the glaze is the
thickest, but
not always. These bubbles are tiny, surface bubbles,
it isn't in the
clay. I wondered if anyone had any run in with this
before. It
wasn't happening before but mostly on these larger pots
that I have
to pour on the glaze. Is there a way to get rid of
these in a re-
fire? Maybe by holding the temp at cone 10 for a bit?
or slow cooling
for the first few hours only?
any advise would be so helpful
Thanks
Lesley
William & Susan Schran User on sat 14 jul 07
On 7/13/07 1:51 PM, "Lesley Anton" wrote:
> Recently, the firings have produced these crazy bubbles all over the
> surface. It seems like they are where the glaze is the thickest, but
> not always. These bubbles are tiny, surface bubbles, it isn't in the
> clay. I wondered if anyone had any run in with this before. It
> wasn't happening before but mostly on these larger pots that I have
> to pour on the glaze. Is there a way to get rid of these in a re-
> fire? Maybe by holding the temp at cone 10 for a bit? or slow cooling
> for the first few hours only?
Have you recently mixed a new batch of the glaze or is this happening with
the same glaze batch you have been using?
Did this occur on all of the pots with this glaze in these firings?
Are the pots made from the same clay or same batch of clay you've been using
previously?
Have the bisque firings changed lately?
--
William "Bill" Schran
wschran@cox.net
wschran@nvcc.edu
http://www.creativecreekartisans.com
Lesley Anton on sat 14 jul 07
thanks for your replies,
To answer your questions in order - here you go :
No, I didn't recently mix a new batch. Yes, it did occur with almost
all of the pots, I have 5 large pots,,all with some sort of surface
bubbling - it is more like an exaggerated lizard skin thing though.
There are areas with the stressed lizard skin, and some with raised
tiny bubbles, They're not blisters, with hollow middles, they are
tiny 1/16" multiple raised pimples, like a densely covered rash. All
the pots are made with Soldate, and with this particular cone 10
matte glaze. The bisque firings haven't changed.
If I were to try to re-fire, which I know most of you clay-arters
don't like to do - but in order to save these pots that were
incredibly labor intensive, thrown and altered things....what might a
soak do, at peak temp? How long should I try to soak? should I go
to cone 11 maybe?
I know these are all experiments and I'll do it anyway but I just was
hoping some of you had had this experience before.
and....to Michael Wendt, thanks for your reply as well. The bisque
firing went fine, so far I haven't had this problem at all with this
glaze, and the bubbles are not the kind you get when you don't
bisque correctly. But I'll try to do the slower early firing thing
next time. that might help. but for now, what do you think about
the pots I have in front of me now? thanks
thanks so much
lesley
Lesley Anton Handmade Ceramic Lighting
323.934.3463
www.lesleyanton.com
On Jul 14, 2007, at 5:46 AM, William & Susan Schran User wrote:
>
> Have you recently mixed a new batch of the glaze or is this
> happening with
> the same glaze batch you have been using?
>
> Did this occur on all of the pots with this glaze in these firings?
>
> Are the pots made from the same clay or same batch of clay you've
> been using
> previously?
>
> Have the bisque firings changed lately?
>
>
> --
> William "Bill" Schran
> wschran@cox.net
> wschran@nvcc.edu
> http://www.creativecreekartisans.com
>
> ______________________________________________________________________
> ________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
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>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
Ron Roy on sun 15 jul 07
Hi Lesley,
Perhaps a new batch of clay?
RR
>thanks for your replies,
>To answer your questions in order - here you go :
>
>No, I didn't recently mix a new batch. Yes, it did occur with almost
>all of the pots, I have 5 large pots,,all with some sort of surface
>bubbling - it is more like an exaggerated lizard skin thing though.
>There are areas with the stressed lizard skin, and some with raised
>tiny bubbles, They're not blisters, with hollow middles, they are
>tiny 1/16" multiple raised pimples, like a densely covered rash. All
>the pots are made with Soldate, and with this particular cone 10
>matte glaze. The bisque firings haven't changed.
>
>If I were to try to re-fire, which I know most of you clay-arters
>don't like to do - but in order to save these pots that were
>incredibly labor intensive, thrown and altered things....what might a
>soak do, at peak temp? How long should I try to soak? should I go
>to cone 11 maybe?
>I know these are all experiments and I'll do it anyway but I just was
>hoping some of you had had this experience before.
>
>and....to Michael Wendt, thanks for your reply as well. The bisque
>firing went fine, so far I haven't had this problem at all with this
>glaze, and the bubbles are not the kind you get when you don't
>bisque correctly. But I'll try to do the slower early firing thing
>next time. that might help. but for now, what do you think about
>the pots I have in front of me now? thanks
>
>thanks so much
>lesley
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Ron Roy on sun 15 jul 07
Hi Lesley,
Send me the recipe - to me directly if you prefer - ronroy@ca.inter.net
Sometines the molecular formula will give some clues about what is
happening and maybe even how to improve the glaze.
RR
>Hi all,
>I am having a problem with a matte glaze that has, so far, not given
>me a problem.
>
>This is a Butter colored, matte glaze, that is very smooth usually.
>I had trouble getting it to be matte in my fiber lined gas kiln but
>with a slow firing down in the cooling I have had great results.
>
>Recently, the firings have produced these crazy bubbles all over the
>surface. It seems like they are where the glaze is the thickest, but
>not always. These bubbles are tiny, surface bubbles, it isn't in the
>clay. I wondered if anyone had any run in with this before. It
>wasn't happening before but mostly on these larger pots that I have
>to pour on the glaze. Is there a way to get rid of these in a re-
>fire? Maybe by holding the temp at cone 10 for a bit? or slow cooling
>for the first few hours only?
>
>any advise would be so helpful
>Thanks
>Lesley
>
>
>Lesley Anton Handmade Ceramic Lighting
>323.934.3463
>www.lesleyanton.com
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
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