Vikki Dow on tue 26 aug 97
Hi Potters,
I have a glaze problem that I am hopng to get help with. I fire a Skutt
1027 KM kiln, in the last load everything was glazed with the same glaze.
It is like a blue celadon glaze, and the body is a white stoneware, B mix.
So I ended up firing this load twice. The first time I fired it to ^9 and
the firing took 11 hours. When I opened the kiln some of the pots where
blistered, not the clay body but the glaze had bubbles,or maybe craters is
a better way to descirbe. So I thought that I had fired the kiln to fast
and probably not hot enough. I fired the load a second time and this time
it went to ^10 and took 14hour to fire. When I opened the kiln this
morning all the pot had some blistering in the glaze to some extent and the
pot that where blistered in the first firing are completely covered.
Any suggestions.
I thought that if a glaze was blistered that it may not have been fired
long enough to get the glaze time to settle down and flatren out after
fluxing. Now it looks like I just over fired the stuff.
Go Well
Libby Still-Hanline
StillTree Pottery
Ron Roy on wed 27 aug 97
Hi Libby,
My best answer would be if I could look at the molecular formula of that
glaze. Send me the recipe - I make part of my living doing this kind of
work - you don't have to worry - I will keep any information private.
Was the first firing longer than usual? Did you just mix up a new batch of
that glaze? Are you using large cones to check your end temperature? Which
B mix are you using? Buy any new materials lately?
>----------------------------Original message----------------------------
When I opened the kiln some of the pots where
>blistered, not the clay body but the glaze had bubbles,or maybe craters is
>a better way to descirbe. So I thought that I had fired the kiln to fast
>and probably not hot enough. I fired the load a second time and this time
>it went to ^10 and took 14hour to fire. When I opened the kiln this
>morning all the pot had some blistering in the glaze to some extent and the
>pot that where blistered in the first firing are completely covered.
Ron Roy
Toronto, Canada
Evenings, call 416 439 2621
Fax, 416 438 7849
Studio: 416-752-7862.
Email ronroy@astral.magic.ca
Home page http://digitalfire.com/education/people/ronroy.htm
Sioux-zan on wed 27 aug 97
Hello Libby,
I've run in to this trouble before. First, I've found if a glaze starts
to bubble, then no matter how many time I fire it it just gets worse.
Have you used this glaze on that same clay body before? I've also had
glazes that just won't work well on one clay body, but they are great on
all the others. I hope this helps.
Peace
Sioux-zanne
>>Hi Potters,
>>I have a glaze problem that I am hopng to get help with. I fire a Skutt
1027 KM kiln, in the last load everything was glazed with the same
glaze.
It is like a blue celadon glaze, and the body is a white stoneware, B
mix.
So I ended up firing this load twice. The first time I fired it to ^9
and
the firing took 11 hours. When I opened the kiln some of the pots where
blistered, not the clay body but the glaze had bubbles,or maybe craters
is
a better way to descirbe. So I thought that I had fired the kiln to fast
and probably not hot enough. I fired the load a second time and this
time
it went to ^10 and took 14hour to fire. When I opened the kiln this
morning all the pot had some blistering in the glaze to some extent and
the
pot that where blistered in the first firing are completely covered.
Any suggestions.
I thought that if a glaze was blistered that it may not have been fired
long enough to get the glaze time to settle down and flatren out after
fluxing. Now it looks like I just over fired the stuff.
Go Well
Libby Still-Hanline
StillTree Pottery
DinaH on mon 9 aug 99
After making up a test batch of RR's modified Floating Blue (which was
beautiful), I made up a bucket full and glazed several large pieces.
They were great. Terrific glaze!
I left town for about a month and when I returned I used the glaze again
but this time when I applied it, it "grazed" in the raw state. I was
using the same clay body. I smoothed the glaze with a damp sponge and my
finger and after firing it, it looked fine but I have an order for a lot
of pieces with that glaze and I sure don't want to have to smooth each
piece.
I added a little water to all my glazes after having not used them for
over a month and it really didn't appear too thick. Is there something
about this glaze that won't let it sit for awhile? 5-6 weeks?
RR's Modified Floating Blue ^6
Neph Sye 41
Gerst. Bor 17
Frit 3134 13
Flint 18
Epk 11
RIO 2
CO carb 1.5
Rutile 4
Thanks for any enlightenment.
Dinah
Mike Bailey on tue 10 aug 99
In message , DinaH writes
Dear Dinah,
My first thought would be the Gerstley Borate. There are also some notes
on 'Ghastly Borate' in the archives.
As an aside, in the U.K. we sometimes get a form of Magnesite that does
a similar thing (only much worse) turning the glaze to a jelly after a
few days.
We also have batches of Calcium Borate Frit that are soluble - leading
to crystals forming in the buckets - but this is a different problem to
the one you mention. I just like to moan about it whenever I get the
chance!
Cheers,
Mike Bailey
>----------------------------Original message----------------------------
>After making up a test batch of RR's modified Floating Blue (which was
>beautiful), I made up a bucket full and glazed several large pieces.
>They were great. Terrific glaze!
>I left town for about a month and when I returned I used the glaze again
>but this time when I applied it, it "grazed" in the raw state. I was
>using the same clay body. I smoothed the glaze with a damp sponge and my
>finger and after firing it, it looked fine but I have an order for a lot
>of pieces with that glaze and I sure don't want to have to smooth each
>piece.
>I added a little water to all my glazes after having not used them for
>over a month and it really didn't appear too thick. Is there something
>about this glaze that won't let it sit for awhile? 5-6 weeks?
>RR's Modified Floating Blue ^6
>Neph Sye 41
>Gerst. Bor 17
>Frit 3134 13
>Flint 18
>Epk 11
>RIO 2
>CO carb 1.5
>Rutile 4
>Thanks for any enlightenment.
>Dinah
>
--
Mike Bailey
Tom Buck on tue 10 aug 99
DinaH:
Your mystery (glaze goes funny) has a cause: it is called gerstley
borate. This mineral contains two susbtances (mostly but not only):
ulexite, NaCaB5O9.8H2O; and colemanite, Ca2B6O11.5H2O. The other stuff is
limestone CaCO3, shale (fossilized clay), possibly some gypsum, and
unknown other junk.
Ulexite is somewhat soluble, especially in warm water, and it
releases Na+ ions that cause some glaze components to come together and
stay together (agglomerate) in larger particles. The Na+ ions can
sometimes cause the big particles to settle rapidly, or in some rare
cases, the glaze mix goes into a gel (jelly like).
SO: don't let this glaze sit around for long, mix smaller
quantities and use it on pots as soon as possible (less than a week). Any
glaze with a large (>15%) amount of GB should be fresh-mixed only, that
is, mix just enough for the current session of glazing (raku people tend
to do this).
Tom Buck
)
tel: 905-389-2339 (westend Lake Ontario, province of Ontario, Canada).
mailing address: 373 East 43rd Street,
Hamilton ON L8T 3E1 Canada
Ron Roy on wed 11 aug 99
Not much I can say except I have made other versions - why not try this one
without any GB - Judith says it works just fine. You can add some of what
you have to it each time you make a new batch.
^6 oxidation
Frit 3134 32.8
Neph Sye 43.3
EPK 13.7
Flint 10.3
You can mix some -lets say a couple of cups - 50/50 with your flocculated
glaze to see if works well. If that is so then you can combine the two
recipes.
The combination of the two is:
GB - 8.5
F3134 - 23.0
Neph Sy - 42.0
EPK - 12.5
Silica - 14.0
Total 100.0
RIO - 2.0
Cobalt carb - 1.5
Rutil 4.0 (you can try straight titanium dioxide to eliminate a variable -
do a test first though.)
RR
>----------------------------Original message----------------------------
>After making up a test batch of RR's modified Floating Blue (which was
>beautiful), I made up a bucket full and glazed several large pieces.
>They were great. Terrific glaze!
>I left town for about a month and when I returned I used the glaze again
>but this time when I applied it, it "grazed" in the raw state. I was
>using the same clay body. I smoothed the glaze with a damp sponge and my
>finger and after firing it, it looked fine but I have an order for a lot
>of pieces with that glaze and I sure don't want to have to smooth each
>piece.
>I added a little water to all my glazes after having not used them for
>over a month and it really didn't appear too thick. Is there something
>about this glaze that won't let it sit for awhile? 5-6 weeks?
>RR's Modified Floating Blue ^6
>Neph Sye 41
>Gerst. Bor 17
>Frit 3134 13
>Flint 18
>Epk 11
>RIO 2
>CO carb 1.5
>Rutile 4
>Thanks for any enlightenment.
>Dinah
Ron Roy
93 Pegasus Trail
Scarborough, Ontario
Canada M1G 3N8
Tel: 416-439-2621
Fax: 416-438-7849
Web page: http://digitalfire.com/education/people/ronroy.htm
Ron Collins on thu 1 nov 01
I have a problem that I asked about once, but am still trying to find =
out what is going on. If you have any input, would you please write me? =
I love the look of Alisa's Desert Wash on the bottoms of my white =
crystalline matt glazed pieces. It is 50-50 zircopax/borax with 4%rutile =
and 8% yellow ocher. The problem is that it spits all over the shelves, =
sometimes taking the white glaze with it. I asked Alisa, and she has no =
problems with it, I fire to cone 6, taking my time, with a slow cool =
down. It is on cone 6 porcelain that I make, or on Axner porcelaneous =
stoneware I brought down with me...does it on both.
I thought I would put the wash on greenware then bisque it on...it =
still spit all over at 04. So it does it, independent of any glaze. I =
then thought maybe I was the only one not dissolving the borax, so I =
dissolved it thoroughly in really hot water, added the rest of stuff, =
but the test came out lichen looking, flaking all over, changed the =
whole character of the slip. =20
Again, I ask, has anyone used this slip, and had this problem? or =
have any thoughts? The only variable that I know of is that I use my =
own ocher that I dig, rather than purchased, but it makes beautiful =
cream/orange Desert slip. I would give it up, but this slip is =
wonderful.-well, almost. Does anyone out there have any input on this? =
Melinda Collins, Antigua, Guatemala
=20
Cindy Strnad on thu 1 nov 01
Hi, Melinda.
In the light of some of the other posts I've seen
lately, why not try calcining your ochre? It might
be worth a try. Maybe something in there is
causing your troubles.
Cindy Strnad
Earthen Vessels Pottery
RR 1, Box 51
Custer, SD 57730
USA
cindy@earthen-vessels-pottery.com
http://www.earthen-vessels-pottery.com
Ababi on fri 2 nov 01
I tried it. As you might learnt not all the written words in our world
are true. This recipe like similar once takes you to the extreme. one
succeed and the other fails. I did not like it.
I will pass it through insight and tell you more. Wait 5 minutes.
Untitled Recipe 1
=================
ULTROX.............. 50.00 50.00%
BORAX............... 50.00 50.00%
========
100.00
Na2O 1.00* 10.64%
ZrO2 2.01 42.55%
B2O3 2.00 23.89%
SiO2 2.22 22.92%
Expan 6.51
Thank you for waiting
No alumina at all probably just pouring down. I think it would work in
raku I mean 950C or lower!
I add here the limit table of Insight for ^6. Remember in such a glaze
we don't need too much the limits but these are good guides, even if we
do the extreme!
Orton Cone 3-7
-------------------
CaO .3-.6
ZnO .1-.25
BaO .1-.3
MgO .1-.2
KNaO .2-.5
B2O3 .3-.5
Al2O3 .2-.35
SiO2 2.5-3.5
When it is .1 it means 0.1
The ultrox\zircopax gives you the silica
The borax gives you Na2O and B2O3
In order to keep it strange, I would add for alumina and other flux
local clay or even local soil.(weigh as dried)
How much?
test one 10% test two 20%.If you don't like the result go down in
amounts. Local soil must be sieved in a fine floor sieve
Ababi Sharon
Kibbutz Shoval- Israel
Glaze addict
sharon@shoval.org.il
http://members4.clubphoto.com/ababi306910/
http://www.milkywayceramics.com/cgallery/asharon.htm
http://www.israelceramics.org/
---------- Original Message ----------
>I have a problem that I asked about once, but am still trying to find
>out what is going on. If you have any input, would you please write
>me? I love the look of Alisa's Desert Wash on the bottoms of my white
>crystalline matt glazed pieces. It is 50-50 zircopax/borax with
>4%rutile and 8% yellow ocher. The problem is that it spits all over the
>shelves, sometimes taking the white glaze with it. I asked Alisa, and
>she has no problems with it, I fire to cone 6, taking my time, with a
>slow cool down. It is on cone 6 porcelain that I make, or on Axner
>porcelaneous stoneware I brought down with me...does it on both.
> I thought I would put the wash on greenware then bisque it on...it
>still spit all over at 04. So it does it, independent of any glaze. I
>then thought maybe I was the only one not dissolving the borax, so I
>dissolved it thoroughly in really hot water, added the rest of stuff,
>but the test came out lichen looking, flaking all over, changed the
>whole character of the slip.
> Again, I ask, has anyone used this slip, and had this problem? or
>have any thoughts? The only variable that I know of is that I use my
>own ocher that I dig, rather than purchased, but it makes beautiful
>cream/orange Desert slip. I would give it up, but this slip is
>wonderful.-well, almost. Does anyone out there have any input on this?
> Melinda Collins, Antigua, Guatemala
>
>________________________________________________________________________
>______
>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.
Kathi LeSueur on fri 1 aug 03
Here's a puzzle for the glaze gurus. I fire to cone 10 reduction. Most
firings take about 12 hours. Purposely very slow once cone 8 is tipping.
I have a problem with pitting for one glaze on vase forms, mainly on the
belly of the piece. The glaze is a satin matte with titanium as an
opacifier. A cobalt/albany slip wash is brushed on. I then spray a matte
copper glaze over the cobalt area. This works just fine for all of my
slab platters. Fine on the lids of casseroles. Fine on my 18" tall slab
lamp bases. No problems with bowls. Just the vases. it matters not how
slow the firing, how longs the soak, or slow the cooling. With but very
few exceptions vases develop pits on the belly of the form. If anyone
can tell me why and how to fix it I'll be forever in your debt and will
cook you a fine dinner if you get to Ann Arbor.
Kathi
Earl Brunner on fri 1 aug 03
It sounds like that might be the area that you trimmed. If that's the
case, do you "burnish" the area with a tool after trimming? I use the
back end of a wooden knife. Trimming can change the surface
characteristics of the clay, you want to get it back as close to like it
was before trimming. I do this on the wheel, at the end of trimming.
Odd that it's just the vases though.
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Kathi
LeSueur
Sent: Thursday, July 31, 2003 10:35 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: glaze mystery
Here's a puzzle for the glaze gurus. I fire to cone 10 reduction. Most
firings take about 12 hours. Purposely very slow once cone 8 is tipping.
I have a problem with pitting for one glaze on vase forms, mainly on the
belly of the piece. The glaze is a satin matte with titanium as an
opacifier. A cobalt/albany slip wash is brushed on. I then spray a matte
copper glaze over the cobalt area. This works just fine for all of my
slab platters. Fine on the lids of casseroles. Fine on my 18" tall slab
lamp bases. No problems with bowls. Just the vases. it matters not how
slow the firing, how longs the soak, or slow the cooling. With but very
few exceptions vases develop pits on the belly of the form. If anyone
can tell me why and how to fix it I'll be forever in your debt and will
cook you a fine dinner if you get to Ann Arbor.
Kathi
Kathi LeSueur on fri 1 aug 03
brunv53@YAHOO.COM wrote:
>It sounds like that might be the area that you trimmed. If that's the
>case, do you "burnish" the area with a tool after trimming?>>>
>
Nope. I do very little trimming on the vases. Just near the foot where I
never have a problem. As an added mystery, another potter started buying
clay from my supplier (armadillo). Like me he loved the clay-how the
glazes looked, how it threw. But... he started getting pitting on the
sides of his vases. I use Balcones which has added iron. He used
Balcones white. Neither of us has been able to eliminate the problem and
I'm considering trying another clay for the vases to see if, maybe, the
problem is something to do with the clay (though I've not a clue what it
could be).
Kathi
>
>
Ron Roy on sat 2 aug 03
Hi Kathi,
Does this happen in any particular part of your kiln?
Tell me - if you refire them do the pits smooth out?
If they do then a glaze adjstment or a soak is the answer.
If they stay the same or get worse - it's the bisque firing.
Ann Arbor is not that far - but far enough I would have to know just what
that dinner containes and it what it will be cooked.
RR
>Here's a puzzle for the glaze gurus. I fire to cone 10 reduction. Most
>firings take about 12 hours. Purposely very slow once cone 8 is tipping.
>I have a problem with pitting for one glaze on vase forms, mainly on the
>belly of the piece. The glaze is a satin matte with titanium as an
>opacifier. A cobalt/albany slip wash is brushed on. I then spray a matte
>copper glaze over the cobalt area. This works just fine for all of my
>slab platters. Fine on the lids of casseroles. Fine on my 18" tall slab
>lamp bases. No problems with bowls. Just the vases. it matters not how
>slow the firing, how longs the soak, or slow the cooling. With but very
>few exceptions vases develop pits on the belly of the form. If anyone
>can tell me why and how to fix it I'll be forever in your debt and will
>cook you a fine dinner if you get to Ann Arbor.
>
>Kathi
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
Kathi LeSueur on sat 2 aug 03
ronroy@TOTAL.NET wrote:
>Hi Kathi,
>
>Does this happen in any particular part of your kiln?>>
>
No, it happens everywhere. Top, bottom, middle, front shelves, back shelves.
>Tell me - if you refire them do the pits smooth out?>>
>
No.
>If they do then a glaze adjstment or a soak is the answer.
>
>If they stay the same or get worse - it's the bisque firing.
>
If the bisque is the answer, what should I change. I bisque to 05 over
the course of 12 hours. Should I take it higher, put in a soak at the
end? But, why only on vase forms or utensil holders?
>Ann Arbor is not that far - but far enough I would have to know just what
>that dinner containes and it what it will be cooked.>>
>
I'm known for being a good cook. Garlic roasted chicken, a great pot
roast, even better brisket with latkes, a great salmon with a
ginger/citrus vinegrette. Not very good with pork since I don't eat it
>
>Kathi
>
>
>
>>
>>
Ron Roy on tue 5 aug 03
Hi Kathi,
I don't know why only tall forms - they are not covered during the bisque
firing - right? Not bisqued upside down - right?
Break one in half and see if there is anything unusual in that area?
Your bisque firing seems long enough - much depends on how dense the
stacking is and if there is enough replacement oxygen available - do I
assume you don't have a kiln vent running?
The crucial part of the bisque firing is between 700C and 900C - best to
try going slower during that time - and leave your top spy open to get more
oxygen - to help burn out any carbon and other stuff.
This is much more a problem with iron bearing clays by the way - should I
assume that?
I do have a weakness for latkes and salmon.
>>Hi Kathi,
>>Does this happen in any particular part of your kiln?>>
>No, it happens everywhere. Top, bottom, middle, front shelves, back shelves.
>>Tell me - if you refire them do the pits smooth out?>>
>No.
>>If they do then a glaze adjstment or a soak is the answer.
>>
>>If they stay the same or get worse - it's the bisque firing.
>If the bisque is the answer, what should I change. I bisque to 05 over
>the course of 12 hours. Should I take it higher, put in a soak at the
>end? But, why only on vase forms or utensil holders?
>>Ann Arbor is not that far - but far enough I would have to know just what
>>that dinner containes and it what it will be cooked.>>
>I'm known for being a good cook. Garlic roasted chicken, a great pot
>roast, even better brisket with latkes, a great salmon with a
>ginger/citrus vinegrette. Not very good with pork since I don't eat it
>>Kathi
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
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