Barney Adams on tue 6 apr 99
Hi,
I had a pretty rough week end. Have'nt felt very well and
while I was unloading one ugly kiln load I succeeded in
smashing most of my kiln shelves. Ouch. Anyhow I will
not let this stop my progress. I have been testing a base glaze
for stains. The initial tile tests went well so I did another test
on both pots and tiles. I have'nt seen 6 month old babies crawl
as much as this stuff did. I mean this stuff shivered right off the
pot on a couple pieces. Do I need to adjust my COE to account
for the stain? Here's two of the tests. I was reading about the Mason
stains requiring 8 to 15% CaO, but I'm on the low end of that.
I'd like to hear want I did wrong and then can I adjust or should
I approach it again with some more (Clayart) insight. (Sorry for
the pun, Tony).
Two Recipes: stain base 1 & stain base 2
========================================
NEPHELINE SYENITE... 30.00 30.00% 26.00 26.00%
GERSTLEY BORATE..... 15.00 15.00% 12.00 12.00%
SPODUMENE........... 10.00 10.00% 5.00 5.00%
WHITING............. 4.00 4.00% 3.00 3.00%
BONE ASH............ 2.00 2.00% 5.00 5.00%
FLINT............... 33.00 33.00% 40.00 40.00%
STRONTIUM CARBONATE. 2.00 2.00% 7.00 7.00%
NYTAL TALC.......... 4.00 4.00% 2.00 2.00%
======== ========
100.00 100.00
CaO 0.43* 7.08% 0.45* 7.43%
MnO2 0.00 0.01% 0.00 0.01%
Li2O 0.09* 0.78% 0.04* 0.39%
MgO 0.16* 1.94% 0.10* 1.20%
K2O 0.06* 1.56% 0.05* 1.35%
Na2O 0.22* 4.01% 0.19* 3.42%
Fe2O3 0.00 0.12% 0.00 0.11%
B2O3 0.22 4.61% 0.18 3.69%
AL2O3 0.35 10.65% 0.27 8.22%
SiO2 3.75 66.76% 3.74 66.54%
P2O5 0.02 0.95% 0.06 2.32%
SrO 0.05* 1.53% 0.17* 5.33%
COST/KG 1.54 2.18
Si:Al 10.65 13.76
SiB:Al 11.35 14.62
EXPAN404.51 435.18
Part of my problem might be trying to transition to Ron's MDT file.
I sometimes have to load it up from the standard MDT if the COE
corresponds to one another.
Barney
Ron Roy on wed 7 apr 99
Hi Barney,
Your glazes check out just fine - ran em both through - the expansion is a
bit low for stoneware - so here is what I did. Took out the Spod - no need
for it except to lower expansion, replaced it with Custer. - took out the
Talc - again MgO is a low expansion flux - replaced it with more whiting.
Redced the Neph Sy a bit - it's high in Al2O3 and added some more Custer to
get a little more KNaO - high expansion fluxes.
If you need a higher expansion - after you test this - add more Custer -
and keep an eye on thr ratio as you do it - this glaze looks like it can
use more alumina - but watch out if you add clay - the expansion will drop
again - use the Custer to get more.
-----------------
NEPH SY............. 20.50 22.40%
Gers Borate 9/97.... 12.00 13.11%
WHITING............. 6.00 6.56%
BONE ASH............ 5.00 5.46%
SILICA.............. 34.00 37.16%
STRONT CARB......... 3.00 3.28%
CUSTER SPAR......... 11.00 12.02%
----------
91.50
FORMULA & ANALYSIS
------------------
*CaO........ .59 10.10%
MnO2.......
*Li2O.......
*MgO........ .06 .72%
*K2O........ .09 2.51%
*Na2O....... .18 3.42%
Fe2O3...... .00 .15%
TIO2.......
B2O3....... .19 4.01%
AL2O3...... .27 8.23%
SiO2....... 3.61 65.84%
P2O5....... .06 2.52%
*SrO........ .08 2.50%
RATIO 13.59
EXPAN 480.47
WEIGHT 329.23
>----------------------------Original message----------------------------
>Hi,
>I had a pretty rough week end. Have'nt felt very well and
>while I was unloading one ugly kiln load I succeeded in
>smashing most of my kiln shelves. Ouch. Anyhow I will
>not let this stop my progress. I have been testing a base glaze
>for stains. The initial tile tests went well so I did another test
>on both pots and tiles. I have'nt seen 6 month old babies crawl
>as much as this stuff did. I mean this stuff shivered right off the
>pot on a couple pieces. Do I need to adjust my COE to account
>for the stain? Here's two of the tests. I was reading about the Mason
>stains requiring 8 to 15% CaO, but I'm on the low end of that.
>I'd like to hear want I did wrong and then can I adjust or should
>I approach it again with some more (Clayart) insight. (Sorry for
>the pun, Tony).
>Part of my problem might be trying to transition to Ron's MDT file.
>I sometimes have to load it up from the standard MDT if the COE
>corresponds to one another.
>
>Barney
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
Barney Adams on thu 8 apr 99
Thanks Ron,
Did you go with replacing the spodumene and MgO with whiting
for the stains or because it replaced a flux of medium expansion
for the ones of lower expansion? I had put the lithia and MgO in
to aid in color development as well as balance out the expansion.
And even though it crawled real badly I liked the color I got.
Does the stain addition (I used 5%) effect expansion?
I'll try the test again on your mix and see how it goes. (as soon as I
replace my shelves) This is being used on the the Tucker mid red
stoneware and mid white. I dont think I've seen crawling that bad
before this. Could I have done anything wrong mixing the batches?
Barney
Ron Roy wrote:
> ----------------------------Original message----------------------------
> Hi Barney,
>
> Your glazes check out just fine - ran em both through - the expansion is a
> bit low for stoneware - so here is what I did. Took out the Spod - no need
> for it except to lower expansion, replaced it with Custer. - took out the
> Talc - again MgO is a low expansion flux - replaced it with more whiting.
> Redced the Neph Sy a bit - it's high in Al2O3 and added some more Custer to
> get a little more KNaO - high expansion fluxes.
> If you need a higher expansion - after you test this - add more Custer -
> and keep an eye on thr ratio as you do it - this glaze looks like it can
> use more alumina - but watch out if you add clay - the expansion will drop
> again - use the Custer to get more.
>
> -----------------
> NEPH SY............. 20.50 22.40%
> Gers Borate 9/97.... 12.00 13.11%
> WHITING............. 6.00 6.56%
> BONE ASH............ 5.00 5.46%
> SILICA.............. 34.00 37.16%
> STRONT CARB......... 3.00 3.28%
> CUSTER SPAR......... 11.00 12.02%
> ----------
> 91.50
> FORMULA & ANALYSIS
> ------------------
> *CaO........ .59 10.10%
> MnO2.......
> *Li2O.......
> *MgO........ .06 .72%
> *K2O........ .09 2.51%
> *Na2O....... .18 3.42%
> Fe2O3...... .00 .15%
> TIO2.......
> B2O3....... .19 4.01%
> AL2O3...... .27 8.23%
> SiO2....... 3.61 65.84%
> P2O5....... .06 2.52%
> *SrO........ .08 2.50%
>
> RATIO 13.59
> EXPAN 480.47
> WEIGHT 329.23
>
> >----------------------------Original message----------------------------
> >Hi,
> >I had a pretty rough week end. Have'nt felt very well and
> >while I was unloading one ugly kiln load I succeeded in
> >smashing most of my kiln shelves. Ouch. Anyhow I will
> >not let this stop my progress. I have been testing a base glaze
> >for stains. The initial tile tests went well so I did another test
> >on both pots and tiles. I have'nt seen 6 month old babies crawl
> >as much as this stuff did. I mean this stuff shivered right off the
> >pot on a couple pieces. Do I need to adjust my COE to account
> >for the stain? Here's two of the tests. I was reading about the Mason
> >stains requiring 8 to 15% CaO, but I'm on the low end of that.
> >I'd like to hear want I did wrong and then can I adjust or should
> >I approach it again with some more (Clayart) insight. (Sorry for
> >the pun, Tony).
>
> >Part of my problem might be trying to transition to Ron's MDT file.
> >I sometimes have to load it up from the standard MDT if the COE
> >corresponds to one another.
> >
> >Barney
>
> 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
Chris Schafale on thu 8 apr 99
Hi Barney,
I was confused by your post. Are you having crawling (bare areas
with rounded edges), shivering (glaze cracking and perhaps coming
off, especially around rims, due to low expansion) or both??? Are
the stains going in the glaze, or are you glazing over stain that
you've put on pots?
Sorry about your rough weekend.
Chris
>
> >----------------------------Original message----------------------------
> >Hi,
> >I had a pretty rough week end. Have'nt felt very well and
> >while I was unloading one ugly kiln load I succeeded in
> >smashing most of my kiln shelves. Ouch. Anyhow I will
> >not let this stop my progress. I have been testing a base glaze
> >for stains. The initial tile tests went well so I did another test
> >on both pots and tiles. I have'nt seen 6 month old babies crawl
> >as much as this stuff did. I mean this stuff shivered right off the
> >pot on a couple pieces. Do I need to adjust my COE to account
> >for the stain? Here's two of the tests. I was reading about the Mason
> >stains requiring 8 to 15% CaO, but I'm on the low end of that.
> >I'd like to hear want I did wrong and then can I adjust or should
> >I approach it again with some more (Clayart) insight. (Sorry for
> >the pun, Tony).
>
> >Part of my problem might be trying to transition to Ron's MDT file.
> >I sometimes have to load it up from the standard MDT if the COE
> >corresponds to one another.
> >
> >Barney
>
> 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
>
>
Light One Candle Pottery
Fuquay-Varina, NC
candle@intrex.net
Barney Adams on fri 9 apr 99
Hi,
I was just having crawling. The shiver was the use of the wrong
term. I added the stains to the glaze (5%). I think Jan Walker may have
hit on the problem. I did'nt let these glazes sit a day as I usually do and
they may not have set right.
Barney
Chris Schafale wrote:
> ----------------------------Original message----------------------------
> Hi Barney,
>
> I was confused by your post. Are you having crawling (bare areas
> with rounded edges), shivering (glaze cracking and perhaps coming
> off, especially around rims, due to low expansion) or both??? Are
> the stains going in the glaze, or are you glazing over stain that
> you've put on pots?
>
> Sorry about your rough weekend.
>
> Chris
>
> >
> > >----------------------------Original message----------------------------
> > >Hi,
> > >I had a pretty rough week end. Have'nt felt very well and
> > >while I was unloading one ugly kiln load I succeeded in
> > >smashing most of my kiln shelves. Ouch. Anyhow I will
> > >not let this stop my progress. I have been testing a base glaze
> > >for stains. The initial tile tests went well so I did another test
> > >on both pots and tiles. I have'nt seen 6 month old babies crawl
> > >as much as this stuff did. I mean this stuff shivered right off the
> > >pot on a couple pieces. Do I need to adjust my COE to account
> > >for the stain? Here's two of the tests. I was reading about the Mason
> > >stains requiring 8 to 15% CaO, but I'm on the low end of that.
> > >I'd like to hear want I did wrong and then can I adjust or should
> > >I approach it again with some more (Clayart) insight. (Sorry for
> > >the pun, Tony).
> >
> > >Part of my problem might be trying to transition to Ron's MDT file.
> > >I sometimes have to load it up from the standard MDT if the COE
> > >corresponds to one another.
> > >
> > >Barney
> >
> > 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
> >
> >
> Light One Candle Pottery
> Fuquay-Varina, NC
> candle@intrex.net
Chris Schafale on sun 11 apr 99
Hi Barney,
Another thought about your crawling glaze. You didn't say what
stains you were using, but it's possible they are raising the
viscosity of your glaze melt, which is causing the crawling. I have
had this happen with zircopax -- when I added it to a glaze that
already was close to wanting to crawl, the glaze crawled much worse,
and even spat blobs off the pots and onto the shelves. Another thing
to look for is any little cracks that form in the raw glaze surface
as it dries on the pot -- chances are, these will become crawls. You
can rub them over with your finger to push glaze into them, but in my
experience, this only works sometimes.
By the way, if you've gotten other helpful responses off-list, and/or
if you've solved the problem, would you mind summarizing on-list,
for the edification of all and the enrichment of the archives?
Chris
> ----------------------------Original message----------------------------
> Hi,
> I had a pretty rough week end. Have'nt felt very well and
> while I was unloading one ugly kiln load I succeeded in
> smashing most of my kiln shelves. Ouch. Anyhow I will
> not let this stop my progress. I have been testing a base glaze
> for stains. The initial tile tests went well so I did another test
> on both pots and tiles. I have'nt seen 6 month old babies crawl
> as much as this stuff did. I mean this stuff shivered right off the
> pot on a couple pieces. Do I need to adjust my COE to account
> for the stain? Here's two of the tests. I was reading about the Mason
> stains requiring 8 to 15% CaO, but I'm on the low end of that.
> I'd like to hear want I did wrong and then can I adjust or should
> I approach it again with some more (Clayart) insight. (Sorry for
> the pun, Tony).
>
> Two Recipes: stain base 1 & stain base 2
> ========================================
> NEPHELINE SYENITE... 30.00 30.00% 26.00 26.00%
> GERSTLEY BORATE..... 15.00 15.00% 12.00 12.00%
> SPODUMENE........... 10.00 10.00% 5.00 5.00%
> WHITING............. 4.00 4.00% 3.00 3.00%
> BONE ASH............ 2.00 2.00% 5.00 5.00%
> FLINT............... 33.00 33.00% 40.00 40.00%
> STRONTIUM CARBONATE. 2.00 2.00% 7.00 7.00%
> NYTAL TALC.......... 4.00 4.00% 2.00 2.00%
> ======== ========
> 100.00 100.00
>
> CaO 0.43* 7.08% 0.45* 7.43%
> MnO2 0.00 0.01% 0.00 0.01%
> Li2O 0.09* 0.78% 0.04* 0.39%
> MgO 0.16* 1.94% 0.10* 1.20%
> K2O 0.06* 1.56% 0.05* 1.35%
> Na2O 0.22* 4.01% 0.19* 3.42%
> Fe2O3 0.00 0.12% 0.00 0.11%
> B2O3 0.22 4.61% 0.18 3.69%
> AL2O3 0.35 10.65% 0.27 8.22%
> SiO2 3.75 66.76% 3.74 66.54%
> P2O5 0.02 0.95% 0.06 2.32%
> SrO 0.05* 1.53% 0.17* 5.33%
>
> COST/KG 1.54 2.18
> Si:Al 10.65 13.76
> SiB:Al 11.35 14.62
> EXPAN404.51 435.18
>
> Part of my problem might be trying to transition to Ron's MDT file.
> I sometimes have to load it up from the standard MDT if the COE
> corresponds to one another.
>
> Barney
>
>
Light One Candle Pottery
Fuquay-Varina, NC
candle@intrex.net
Barney Adams on mon 12 apr 99
Hi Chris,
I think the main problem was not letting the glaze mix set for 24 hours.
I still have some of the batch which I'll test when I get kiln shelves.
I was unloading the kiln and wondering about the crawling more
than paying attention to how I was stacking the shelves and with the
last shelf the entire load tipped and smashed. I just bought my enviro
vent so I have to wait til next week before I can budget to buy some
more shelves. As soon as I pick up the shelves I entend to do some
more tests. These will include mixing up Ron's version of the glaze,
re-firing the original since it's been sitting for a week, and possibly
trying another mix possibly going a little high on the COE.
The stain I used was the Mason stain called blackberry wine. I got two
very nice colors off two of my bases. I used 5% with both. I have some
other stains to test with. I would like to keep the Li2O and MgO in the
glaze as I like the colors they seem to develop. I'll give you all a synopsis
some time week after next.
Whatever has been in the air of late has'nt quite left yet. I think the
brushes
on my Pacifica are going after one year. I've been having trouble centering
anything over 10 lbs. I can not complain though I have been on the wheel
more or less daily and weekends usually constantly. Then Saturday I went
to my drawing class and my car is finally giving up the ghost (it's been with
me for about 12 years). I'm not complaining mind you I expected each of these
things just not all within a week.
The good news is I replaced the peephole brick on my kiln with no incidents.
I'll tell you the dumb mistake story sometime how I learned the true meaning
of "soft brick".
Barney
Chris Schafale wrote:
> ----------------------------Original message----------------------------
> Hi Barney,
>
> Another thought about your crawling glaze. You didn't say what
> stains you were using, but it's possible they are raising the
> viscosity of your glaze melt, which is causing the crawling. I have
> had this happen with zircopax -- when I added it to a glaze that
> already was close to wanting to crawl, the glaze crawled much worse,
> and even spat blobs off the pots and onto the shelves. Another thing
> to look for is any little cracks that form in the raw glaze surface
> as it dries on the pot -- chances are, these will become crawls. You
> can rub them over with your finger to push glaze into them, but in my
> experience, this only works sometimes.
>
> By the way, if you've gotten other helpful responses off-list, and/or
> if you've solved the problem, would you mind summarizing on-list,
> for the edification of all and the enrichment of the archives?
>
> Chris
fox hollow on mon 12 apr 99
I've had years of crawling, flinging itself onto hearby pots, Gerstley Borate
containing glaze. I wasn't willing to give up the glaze and fought through
with lots of recommendations. Thinking that the glaze might be too thick, I
thinned it. Wrong! As a Gerstley Borate glaze sits around it just LOOKS like
it is getting thicker, but if the top on the glaze bucket is fastened down
tight it is not getting thicker, just doing it's flocculate thing. Anyway,
one thing I did was quit thinning the glaze. The extra water screws up the
glaze formula. Another major deal with Gerstley Borate is that is isn't fond
of firing too fast at the beginning of the cycle, and it likes to be perfectly
dry before it goes into the kiln. There are many many more considerations but
these are the two that helped my own particular problem with crazing.
Jean at Fox Hollow Pottery in the hills of Kentucky.
Chris Schafale wrote:
> ----------------------------Original message----------------------------
> Hi Barney,
>
> Another thought about your crawling glaze. You didn't say what
> stains you were using, but it's possible they are raising the
> viscosity of your glaze melt, which is causing the crawling. I have
> had this happen with zircopax -- when I added it to a glaze that
> already was close to wanting to crawl, the glaze crawled much worse,
> and even spat blobs off the pots and onto the shelves. Another thing
> to look for is any little cracks that form in the raw glaze surface
> as it dries on the pot -- chances are, these will become crawls. You
> can rub them over with your finger to push glaze into them, but in my
> experience, this only works sometimes.
>
> By the way, if you've gotten other helpful responses off-list, and/or
> if you've solved the problem, would you mind summarizing on-list,
> for the edification of all and the enrichment of the archives?
>
> Chris
>
> > ----------------------------Original message----------------------------
> > Hi,
> > I had a pretty rough week end. Have'nt felt very well and
> > while I was unloading one ugly kiln load I succeeded in
> > smashing most of my kiln shelves. Ouch. Anyhow I will
> > not let this stop my progress. I have been testing a base glaze
> > for stains. The initial tile tests went well so I did another test
> > on both pots and tiles. I have'nt seen 6 month old babies crawl
> > as much as this stuff did. I mean this stuff shivered right off the
> > pot on a couple pieces. Do I need to adjust my COE to account
> > for the stain? Here's two of the tests. I was reading about the Mason
> > stains requiring 8 to 15% CaO, but I'm on the low end of that.
> > I'd like to hear want I did wrong and then can I adjust or should
> > I approach it again with some more (Clayart) insight. (Sorry for
> > the pun, Tony).
> >
> > Two Recipes: stain base 1 & stain base 2
> > ========================================
> > NEPHELINE SYENITE... 30.00 30.00% 26.00 26.00%
> > GERSTLEY BORATE..... 15.00 15.00% 12.00 12.00%
> > SPODUMENE........... 10.00 10.00% 5.00 5.00%
> > WHITING............. 4.00 4.00% 3.00 3.00%
> > BONE ASH............ 2.00 2.00% 5.00 5.00%
> > FLINT............... 33.00 33.00% 40.00 40.00%
> > STRONTIUM CARBONATE. 2.00 2.00% 7.00 7.00%
> > NYTAL TALC.......... 4.00 4.00% 2.00 2.00%
> > ======== ========
> > 100.00 100.00
> >
> > CaO 0.43* 7.08% 0.45* 7.43%
> > MnO2 0.00 0.01% 0.00 0.01%
> > Li2O 0.09* 0.78% 0.04* 0.39%
> > MgO 0.16* 1.94% 0.10* 1.20%
> > K2O 0.06* 1.56% 0.05* 1.35%
> > Na2O 0.22* 4.01% 0.19* 3.42%
> > Fe2O3 0.00 0.12% 0.00 0.11%
> > B2O3 0.22 4.61% 0.18 3.69%
> > AL2O3 0.35 10.65% 0.27 8.22%
> > SiO2 3.75 66.76% 3.74 66.54%
> > P2O5 0.02 0.95% 0.06 2.32%
> > SrO 0.05* 1.53% 0.17* 5.33%
> >
> > COST/KG 1.54 2.18
> > Si:Al 10.65 13.76
> > SiB:Al 11.35 14.62
> > EXPAN404.51 435.18
> >
> > Part of my problem might be trying to transition to Ron's MDT file.
> > I sometimes have to load it up from the standard MDT if the COE
> > corresponds to one another.
> >
> > Barney
> >
> >
> Light One Candle Pottery
> Fuquay-Varina, NC
> candle@intrex.net
Tom Wirt on wed 14 apr 99
Subject: Re: Glaze question-Stains
>----------------------------Original message----------------------------
>I've had years of crawling, flinging itself onto hearby pots, Gerstley
Borate
>containing glaze. I wasn't willing to give up the glaze and fought through
>with lots of recommendations. Thinking that the glaze might be too thick,
I
>thinned it. Wrong! As a Gerstley Borate glaze sits around it just LOOKS
like
>it is getting thicker, but if the top on the glaze bucket is fastened down
>tight it is not getting thicker, just doing it's flocculate thing. Anyway,
>one thing I did was quit thinning the glaze. The extra water screws up the
>glaze formula. Another major deal with Gerstley Borate is that is isn't
fond
>of firing too fast at the beginning of the cycle, and it likes to be
perfectly
>dry before it goes into the kiln. There are many many more considerations
but
>these are the two that helped my own particular problem with crazing.
Jean, Chris, Barney, et., al.
Here's what we've been learning about thinning glazes. Many others know
this stuff, and Ron correct me if I've got something wrong.
Jean, you are right, the adding of water just compounds the problem. The
way to "thin" the glaze is with a deflocculant...e.g.. Darvan 7. Or some
material that makes the glaze slip alkaline/basic.
Actually, when you first mix the glaze, mix with the minimum of water to be
able to sieve it, then add the deflocculant to give apparent thinness. The
way we used to do it, thin it out then flocculate it with Epsom salts gave
us the crawling problems in spades. Apparent;y different Gerstley Borates
have different tendencies to crawl.
Tom Wirt
Ron Roy on sat 17 apr 99
Hi Barney,
Yes I am catching up but miles to go ....
Yes - I replaced the lithia and magnesium to raise the expansion - not to
help the stains - you will see if that happens. Yes - stains will affect
expansion - but each stain will affect in a different way - no way to tell
which way except by experimenting.
The crawling can be from fast drying - is it right that there is no clay in
the recipe? If so you better add 2% bentonite to help keep the glaze from
crawling - gives a tougher surface. Make sure the glaze is completely dry
before starting to fire.
RR
>----------------------------Original message----------------------------
>Thanks Ron,
>Did you go with replacing the spodumene and MgO with whiting
>for the stains or because it replaced a flux of medium expansion
>for the ones of lower expansion? I had put the lithia and MgO in
>to aid in color development as well as balance out the expansion.
>And even though it crawled real badly I liked the color I got.
>Does the stain addition (I used 5%) effect expansion?
>
>I'll try the test again on your mix and see how it goes. (as soon as I
>replace my shelves) This is being used on the the Tucker mid red
>stoneware and mid white. I dont think I've seen crawling that bad
>before this. Could I have done anything wrong mixing the batches?
>
>Barney
>
>Ron Roy wrote:
>
>> ----------------------------Original message----------------------------
>> Hi Barney,
>>
>> Your glazes check out just fine - ran em both through - the expansion is a
>> bit low for stoneware - so here is what I did. Took out the Spod - no need
>> for it except to lower expansion, replaced it with Custer. - took out the
>> Talc - again MgO is a low expansion flux - replaced it with more whiting.
>> Redced the Neph Sy a bit - it's high in Al2O3 and added some more Custer to
>> get a little more KNaO - high expansion fluxes.
>> If you need a higher expansion - after you test this - add more Custer -
>> and keep an eye on thr ratio as you do it - this glaze looks like it can
>> use more alumina - but watch out if you add clay - the expansion will drop
>> again - use the Custer to get more.
>>
>> -----------------
>> NEPH SY............. 20.50 22.40%
>> Gers Borate 9/97.... 12.00 13.11%
>> WHITING............. 6.00 6.56%
>> BONE ASH............ 5.00 5.46%
>> SILICA.............. 34.00 37.16%
>> STRONT CARB......... 3.00 3.28%
>> CUSTER SPAR......... 11.00 12.02%
>> ----------
>> 91.50
>> FORMULA & ANALYSIS
>> ------------------
>> *CaO........ .59 10.10%
>> MnO2.......
>> *Li2O.......
>> *MgO........ .06 .72%
>> *K2O........ .09 2.51%
>> *Na2O....... .18 3.42%
>> Fe2O3...... .00 .15%
>> TIO2.......
>> B2O3....... .19 4.01%
>> AL2O3...... .27 8.23%
>> SiO2....... 3.61 65.84%
>> P2O5....... .06 2.52%
>> *SrO........ .08 2.50%
>>
>> RATIO 13.59
>> EXPAN 480.47
>> WEIGHT 329.23
>>
>> >----------------------------Original message----------------------------
>> >Hi,
>> >I had a pretty rough week end. Have'nt felt very well and
>> >while I was unloading one ugly kiln load I succeeded in
>> >smashing most of my kiln shelves. Ouch. Anyhow I will
>> >not let this stop my progress. I have been testing a base glaze
>> >for stains. The initial tile tests went well so I did another test
>> >on both pots and tiles. I have'nt seen 6 month old babies crawl
>> >as much as this stuff did. I mean this stuff shivered right off the
>> >pot on a couple pieces. Do I need to adjust my COE to account
>> >for the stain? Here's two of the tests. I was reading about the Mason
>> >stains requiring 8 to 15% CaO, but I'm on the low end of that.
>> >I'd like to hear want I did wrong and then can I adjust or should
>> >I approach it again with some more (Clayart) insight. (Sorry for
>> >the pun, Tony).
>>
>> >Part of my problem might be trying to transition to Ron's MDT file.
>> >I sometimes have to load it up from the standard MDT if the COE
>> >corresponds to one another.
>> >
>> >Barney
>>
>> 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 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
Barney Adams on mon 19 apr 99
Hi,
I have the results of my glaze test, and I can sum it up in one word...
C R A W L I N G!. I have some serious shelf grinding because this
stuff crawled so bad it was jumping several inches off the pot. The
old glaze tests were the worse so it is not due to the glaze mix sitting
for 24 hours. I made sure the glaze dried before firing. My firing
was slow to cone 6 about 120 degress F to the top (just over 14 hours).
I had a 15 minute soak at the top. The 6 cone was about half mast.
One pot spit 3 ink blot blobs on one shelf.
I did not get a chance to test the new recipe with some epk added as when
I went to glaze that batch was just too thin. I did'nt try the bentonite as
I read this after I started the firing.
One thing on some of the pots that crazed. They seem to be glazed over all
but only the stained portion crawled. Especially on the whiteware pieces.
I have a very clear glaze over the piece. I think this can be one of two
things happening. This is normal for crawling and has to do with the flux
of the glaze reacting with the body, or I'm getting glass from the silica. If
the silica is giving me the clear coating (one piece has a layer of clear in
the bottom) could this be due to my using Flint with 325 mesh. I don't grind
my glazes, but I had read that this could be the cause for crawling (and just
about anything else). I had originally got the stain to add to some porcelain
body and decided to try a base glaze to see what I could get...Sheesh.
I've got another problem with a couple pre-mixed glazes from the supplier.
They pinhole real bad. I've tried re-firing these but the only way I've cleaned
them up was to re-apply one of my glazes an refire. My guess the problem with
these pinholes maybe the thickness I'm mixing these glazes too. I usually try
for a heavy cream although I've found some glazes that like to be thinner. I've
tried longer soaks and slower cool downs but all that tend to do is give me a
firing close to cone 7 and still get pinholes. These glazes also seem to be
the runniest. Maybe I should try re-sieving the glaze? Is there anything else?
Barney
With some nice colors on parts of the pots.
Ron Roy wrote:
> ----------------------------Original message----------------------------
> Hi Barney,
>
> Yes I am catching up but miles to go ....
>
> Yes - I replaced the lithia and magnesium to raise the expansion - not to
> help the stains - you will see if that happens. Yes - stains will affect
> expansion - but each stain will affect in a different way - no way to tell
> which way except by experimenting.
>
> The crawling can be from fast drying - is it right that there is no clay in
> the recipe? If so you better add 2% bentonite to help keep the glaze from
> crawling - gives a tougher surface. Make sure the glaze is completely dry
> before starting to fire.
>
> RR
>
> >----------------------------Original message----------------------------
> >Thanks Ron,
> >Did you go with replacing the spodumene and MgO with whiting
> >for the stains or because it replaced a flux of medium expansion
> >for the ones of lower expansion? I had put the lithia and MgO in
> >to aid in color development as well as balance out the expansion.
> >And even though it crawled real badly I liked the color I got.
> >Does the stain addition (I used 5%) effect expansion?
> >
> >I'll try the test again on your mix and see how it goes. (as soon as I
> >replace my shelves) This is being used on the the Tucker mid red
> >stoneware and mid white. I dont think I've seen crawling that bad
> >before this. Could I have done anything wrong mixing the batches?
> >
> >Barney
> >
> >Ron Roy wrote:
> >
> >> ----------------------------Original message----------------------------
> >> Hi Barney,
> >>
> >> Your glazes check out just fine - ran em both through - the expansion is a
> >> bit low for stoneware - so here is what I did. Took out the Spod - no need
> >> for it except to lower expansion, replaced it with Custer. - took out the
> >> Talc - again MgO is a low expansion flux - replaced it with more whiting.
> >> Redced the Neph Sy a bit - it's high in Al2O3 and added some more Custer to
> >> get a little more KNaO - high expansion fluxes.
> >> If you need a higher expansion - after you test this - add more Custer -
> >> and keep an eye on thr ratio as you do it - this glaze looks like it can
> >> use more alumina - but watch out if you add clay - the expansion will drop
> >> again - use the Custer to get more.
> >>
> >> -----------------
> >> NEPH SY............. 20.50 22.40%
> >> Gers Borate 9/97.... 12.00 13.11%
> >> WHITING............. 6.00 6.56%
> >> BONE ASH............ 5.00 5.46%
> >> SILICA.............. 34.00 37.16%
> >> STRONT CARB......... 3.00 3.28%
> >> CUSTER SPAR......... 11.00 12.02%
> >> ----------
> >> 91.50
> >> FORMULA & ANALYSIS
> >> ------------------
> >> *CaO........ .59 10.10%
> >> MnO2.......
> >> *Li2O.......
> >> *MgO........ .06 .72%
> >> *K2O........ .09 2.51%
> >> *Na2O....... .18 3.42%
> >> Fe2O3...... .00 .15%
> >> TIO2.......
> >> B2O3....... .19 4.01%
> >> AL2O3...... .27 8.23%
> >> SiO2....... 3.61 65.84%
> >> P2O5....... .06 2.52%
> >> *SrO........ .08 2.50%
> >>
> >> RATIO 13.59
> >> EXPAN 480.47
> >> WEIGHT 329.23
> >>
> >> >----------------------------Original message----------------------------
> >> >Hi,
> >> >I had a pretty rough week end. Have'nt felt very well and
> >> >while I was unloading one ugly kiln load I succeeded in
> >> >smashing most of my kiln shelves. Ouch. Anyhow I will
> >> >not let this stop my progress. I have been testing a base glaze
> >> >for stains. The initial tile tests went well so I did another test
> >> >on both pots and tiles. I have'nt seen 6 month old babies crawl
> >> >as much as this stuff did. I mean this stuff shivered right off the
> >> >pot on a couple pieces. Do I need to adjust my COE to account
> >> >for the stain? Here's two of the tests. I was reading about the Mason
> >> >stains requiring 8 to 15% CaO, but I'm on the low end of that.
> >> >I'd like to hear want I did wrong and then can I adjust or should
> >> >I approach it again with some more (Clayart) insight. (Sorry for
> >> >the pun, Tony).
> >>
> >> >Part of my problem might be trying to transition to Ron's MDT file.
> >> >I sometimes have to load it up from the standard MDT if the COE
> >> >corresponds to one another.
> >> >
> >> >Barney
> >>
> >> 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 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
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