April Pauley Mink on fri 7 apr 00
Greetings Clayarters,
I am one of the faithful lurkers. This is my second post to the list, so as
so many have said--this is an awesome resource, and I wish that I could
have met some of you in Denver, but I will be able to attend NCECA next
year in Charlotte and hope to meet the famed there.
Okay, a while back I found a recipe on Clayart for a fake ash cone 6
electric glaze that is absolutely gorgeous as all have said that commmented
on it. It has wonderful rivulets and the redart clay gives these beautiful
background speckles and streaks of bronzy red. Anyway, it is coming out
with bubbles on the surface, not pinholes, not really what I would call a
blister, although, I cannot recall working with a glaze that blisters. To
give an accurate, although graphic, description, it looks like bubbles of
spit on the surface. It does not happen everywhere on the surface though.
The surface of the bubbles is soft enough that you can flick it with a
fingernail and break the bubbles and then be left with something that looks
like a pinhole. I do not see that it is on one side of a pot, a side that
may have been close to another pot with a different type of glaze or
anything. Is this a result of overfiring perhaps? The recipe calls for bone
ash as you can see below, and I was wondering if the sythetic bone ashes
out there have any sorts of problems like I am seeing. I am firing to
witness cone 6 in an L&L 7.5 cubic foot kiln with a one hour soak,
temperature very gradually going down during the soak. I am using
Highwater's Ellen Buff clay. It is such a beautiful glaze (other than the
spit looking bubbles), particularly for one working currently in the
confines of electric firing. Could any one look at the recipe and give
their thoughts? Thank you in advance for your time.
Golden Fake Ash Glaze
Redart 27
Dolomite 24
Barium Carb 12 (I have substituted 9 of strontium carbonate instead)
Ball Clay 20
Lithium Carb 2
Gertsley Borate 10
Bone Ash 5
Regards to all out there in Clayart cyberspace. South Carolina is gorgeous
now--lots of frilly spring dresses on the trees.
April Mink
Alex Solla on sat 8 apr 00
April-
I did quite a bit of playing around with High-Ca
glazes (ash both fake and real) when I was in grad
school... from your description it sounds like 2
different things: you could be over firing which is
easy enough to fix. The other could be off-gasing from
your claybody. Fix that by firing your bisque a bit
hotter.
I found myself having some problems with a weakened
bisque from having too porous a bisque. The subsequent
deep absorption of solubles from real ash glazes was
too strong and occasionally acted as a body flux...
had to be careful. Upped the bisque and that problem
dissappeared.
Another glaze had the spit bubbles you describe...
they only went away with adding some more "body" to
the glaze. Some extra silica, and a bit of spar
helped. Effectively raised the melting temp of the
glaze, and you could do the same by simply firing
cooler.
If this has confused the matter, email me off the list
and I will see if I can clarify
-Alex
--- April Pauley Mink
wrote:
> ----------------------------Original
> message----------------------------
> Greetings Clayarters,
> I am one of the faithful lurkers. This is my second
> post to the list, so as
> so many have said--this is an awesome resource, and
> I wish that I could
> have met some of you in Denver, but I will be able
> to attend NCECA next
> year in Charlotte and hope to meet the famed there.
> Okay, a while back I found a recipe on Clayart for a
> fake ash cone 6
> electric glaze that is absolutely gorgeous as all
> have said that commmented
> on it. It has wonderful rivulets and the redart
> clay gives these beautiful
> background speckles and streaks of bronzy red.
> Anyway, it is coming out
> with bubbles on the surface, not pinholes, not
> really what I would call a
> blister, although, I cannot recall working with a
> glaze that blisters. To
> give an accurate, although graphic, description, it
> looks like bubbles of
> spit on the surface. It does not happen everywhere
> on the surface though.
> The surface of the bubbles is soft enough that you
> can flick it with a
> fingernail and break the bubbles and then be left
> with something that looks
> like a pinhole. I do not see that it is on one side
> of a pot, a side that
> may have been close to another pot with a different
> type of glaze or
> anything. Is this a result of overfiring perhaps?
> The recipe calls for bone
> ash as you can see below, and I was wondering if the
> sythetic bone ashes
> out there have any sorts of problems like I am
> seeing. I am firing to
> witness cone 6 in an L&L 7.5 cubic foot kiln with a
> one hour soak,
> temperature very gradually going down during the
> soak. I am using
> Highwater's Ellen Buff clay. It is such a beautiful
> glaze (other than the
> spit looking bubbles), particularly for one working
> currently in the
> confines of electric firing. Could any one look at
> the recipe and give
> their thoughts? Thank you in advance for your time.
> Golden Fake Ash Glaze
>
> Redart 27
> Dolomite 24
> Barium Carb 12 (I have substituted 9 of strontium
> carbonate instead)
> Ball Clay 20
> Lithium Carb 2
> Gertsley Borate 10
> Bone Ash 5
>
> Regards to all out there in Clayart cyberspace.
> South Carolina is gorgeous
> now--lots of frilly spring dresses on the trees.
> April Mink
>
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Dave Finkelnburg on sat 8 apr 00
April,
I had exactly this problem last fall with a bunch of cone 6 glazes, all
of which happened to also contain Gerstley borate. You might try this for a
quick test. Do you have any Ferro frit 3134? If so, mix a batch of this
glaze with no Gerstley borate, but with the same amount of 3134. I looked
at Insight, and it's pretty close as a sub, using the "average" current GB
analysis I have. Anyway, if that gets rid of the blisters, you have your
answer.
I have also seen this with lithium, but I'd start with the GB for a
quick inquiry before I did anything very drastic. I'd make a small batch,
100 to 500 grams, and test on a tile, before I'd put the test on anything I
wanted.
Good luck!
Dave Finkelnburg in sunny, chilly Idaho
-----Original Message-----
From: April Pauley Mink
To: CLAYART@LSV.UKY.EDU
Date: Friday, April 07, 2000 11:03 AM
Subject: beautiful, but bubbled up fake ash glaze
----------------------------Original message----------------------------
Greetings Clayarters,
I am one of the faithful lurkers. This is my second post to the list, so as
so many have said--this is an awesome resource, and I wish that I could
have met some of you in Denver, but I will be able to attend NCECA next
year in Charlotte and hope to meet the famed there.
Okay, a while back I found a recipe on Clayart for a fake ash cone 6
electric glaze that is absolutely gorgeous as all have said that commmented
on it. It has wonderful rivulets and the redart clay gives these beautiful
background speckles and streaks of bronzy red. Anyway, it is coming out
with bubbles on the surface, not pinholes, not really what I would call a
blister, although, I cannot recall working with a glaze that blisters. To
give an accurate, although graphic, description, it looks like bubbles of
spit on the surface. It does not happen everywhere on the surface though.
The surface of the bubbles is soft enough that you can flick it with a
fingernail and break the bubbles and then be left with something that looks
like a pinhole. I do not see that it is on one side of a pot, a side that
may have been close to another pot with a different type of glaze or
anything. Is this a result of overfiring perhaps? The recipe calls for bone
ash as you can see below, and I was wondering if the sythetic bone ashes
out there have any sorts of problems like I am seeing. I am firing to
witness cone 6 in an L&L 7.5 cubic foot kiln with a one hour soak,
temperature very gradually going down during the soak. I am using
Highwater's Ellen Buff clay. It is such a beautiful glaze (other than the
spit looking bubbles), particularly for one working currently in the
confines of electric firing. Could any one look at the recipe and give
their thoughts? Thank you in advance for your time.
Golden Fake Ash Glaze
Redart 27
Dolomite 24
Barium Carb 12 (I have substituted 9 of strontium carbonate instead)
Ball Clay 20
Lithium Carb 2
Gertsley Borate 10
Bone Ash 5
Regards to all out there in Clayart cyberspace. South Carolina is gorgeous
now--lots of frilly spring dresses on the trees.
April Mink
Cindy Strnad on sat 8 apr 00
April,
I'm sure you'll get more helpful replies, but based on my own past
experience, I'd suspect the dolomite. If I were better at it, I'd try and
reformulate your glaze using talc instead, but I'll leave that to the
experts.
Cindy Strnad
earthenv@gwtc.net
Earthen Vessels Pottery
RR 1, Box 51
Custer, SD 57730
chappelear on sat 8 apr 00
The bubbling you describe happens to me too when I apply the glaze too
thickly.
-----Original Message-----
From: April Pauley Mink
To: CLAYART@LSV.UKY.EDU
Date: Friday, April 07, 2000 1:03 PM
Subject: beautiful, but bubbled up fake ash glaze
----------------------------Original message----------------------------
Greetings Clayarters,
I am one of the faithful lurkers. This is my second post to the list, so as
so many have said--this is an awesome resource, and I wish that I could
have met some of you in Denver, but I will be able to attend NCECA next
year in Charlotte and hope to meet the famed there.
Okay, a while back I found a recipe on Clayart for a fake ash cone 6
electric glaze that is absolutely gorgeous as all have said that commmented
on it. It has wonderful rivulets and the redart clay gives these beautiful
background speckles and streaks of bronzy red. Anyway, it is coming out
with bubbles on the surface, not pinholes, not really what I would call a
blister, although, I cannot recall working with a glaze that blisters. To
give an accurate, although graphic, description, it looks like bubbles of
spit on the surface. It does not happen everywhere on the surface though.
The surface of the bubbles is soft enough that you can flick it with a
fingernail and break the bubbles and then be left with something that looks
like a pinhole. I do not see that it is on one side of a pot, a side that
may have been close to another pot with a different type of glaze or
anything. Is this a result of overfiring perhaps? The recipe calls for bone
ash as you can see below, and I was wondering if the sythetic bone ashes
out there have any sorts of problems like I am seeing. I am firing to
witness cone 6 in an L&L 7.5 cubic foot kiln with a one hour soak,
temperature very gradually going down during the soak. I am using
Highwater's Ellen Buff clay. It is such a beautiful glaze (other than the
spit looking bubbles), particularly for one working currently in the
confines of electric firing. Could any one look at the recipe and give
their thoughts? Thank you in advance for your time.
Golden Fake Ash Glaze
Redart 27
Dolomite 24
Barium Carb 12 (I have substituted 9 of strontium carbonate instead)
Ball Clay 20
Lithium Carb 2
Gertsley Borate 10
Bone Ash 5
Regards to all out there in Clayart cyberspace. South Carolina is gorgeous
now--lots of frilly spring dresses on the trees.
April Mink
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