Paul Lewing on mon 23 jun 03
OK, Guys, if Clayart's gotten a bit boring for you, I have an old-fashioned
glaze mystery for you. I use a number of different base glazes and color
them with various stuff. Recently I've been testing some grey Mason stains
in three different (but not THAT different) cone 5 oxidation base glazes.
In two of them the chrome-based grey stains all consistently come out some
pink or lavender shade and in the other they come out grey. I don't see
that much difference among them and I'm wondering if any of you can spot
what's making the difference.
Here are the two in which grey stains always come out pink.
Two Recipes: 5CL & SC40F
========================
CUSTER FELDSPAR.......... 26.10 22.30
FLINT.................... 25.20 22.30
EP KAOLIN................ 14.00 9.90
FRIT 3134................ 14.00 28.00
WHITING.................. 10.20 11.80
DOLOMITE................. 5.60 3.60
BARIUM CARBONATE......... 4.60
BENTONITE................ 2.10
========= =========
99.70 100.00
BaO 0.07*
CaO 0.63* 0.71*
MgO 0.10* 0.06*
K2O 0.09* 0.07*
Na2O 0.11* 0.16*
TiO2 0.00 0.00
Al2O3 0.30 0.22
B2O3 0.15 0.26
P2O5 0.00 0.00
SiO2 2.84 2.57
Si:Al 9.41 11.62
SiB:Al 9.89 12.80
Expan 7.40 7.65
Here is the recipe in which the grey stains all come out grey:
5 X 20
====================================
CUSTER FELDSPAR.......... 20.00
FRIT 3134................ 20.00
WOLLASTONITE............. 20.00
EPK KAOLIN............... 20.00
SILICA................... 20.00
=========
100.00
CaO 0.79*
MgO 0.00*
K2O 0.07*
Na2O 0.14*
TiO2 0.00
Al2O3 0.35
B2O3 0.21
P2O5 0.00
SiO2 3.35
Si:Al 9.65
SiB:Al 10.27
Expan 7.03
I thought at first it was the small amount of barium in the 5Cl that was
causing the grey stains to go pink. Until I tried them in the SC40F. By
the way, there is no opacifier of any kind, much less tin oxide, in any of
these. And this color response will happen if samples of all three are side
by side in the same firing, so it's not temperature, cooling rate, or stuff
volatilizing. It's not Si:Al ratio, as the one that stays grey is the one
in the middle for ratio. Except for the barium in the 5CL, they all have
the same oxides in different proportions. The 5x20 has marginally more CaO
than the SC40F and marginally more Al2O3 than the 5CL. The only thing it's
got significantly more of than either of the others is the SiO2.
Could that be it? If so, can anyone explain to me why that's making the
difference? Anybody else want to venture a guess?
Paul Lewing, Seattle
Earl Brunner on tue 24 jun 03
Well, you are getting a chrome pink aren't you......The big difference I
see is the MgO.....
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Paul Lewing
Sent: Monday, June 23, 2003 10:48 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Grey/pink glaze mystery
OK, Guys, if Clayart's gotten a bit boring for you, I have an
old-fashioned
glaze mystery for you. I use a number of different base glazes and
color
them with various stuff. Recently I've been testing some grey Mason
stains
in three different (but not THAT different) cone 5 oxidation base
glazes.
In two of them the chrome-based grey stains all consistently come out
some
pink or lavender shade and in the other they come out grey. I don't see
that much difference among them and I'm wondering if any of you can spot
what's making the difference.
Here are the two in which grey stains always come out pink.
Two Recipes: 5CL & SC40F
========================
CUSTER FELDSPAR.......... 26.10 22.30
FLINT.................... 25.20 22.30
EP KAOLIN................ 14.00 9.90
FRIT 3134................ 14.00 28.00
WHITING.................. 10.20 11.80
DOLOMITE................. 5.60 3.60
BARIUM CARBONATE......... 4.60
BENTONITE................ 2.10
========= =========
99.70 100.00
BaO 0.07*
CaO 0.63* 0.71*
MgO 0.10* 0.06*
K2O 0.09* 0.07*
Na2O 0.11* 0.16*
TiO2 0.00 0.00
Al2O3 0.30 0.22
B2O3 0.15 0.26
P2O5 0.00 0.00
SiO2 2.84 2.57
Si:Al 9.41 11.62
SiB:Al 9.89 12.80
Expan 7.40 7.65
Here is the recipe in which the grey stains all come out grey:
5 X 20
====================================
CUSTER FELDSPAR.......... 20.00
FRIT 3134................ 20.00
WOLLASTONITE............. 20.00
EPK KAOLIN............... 20.00
SILICA................... 20.00
=========
100.00
CaO 0.79*
MgO 0.00*
K2O 0.07*
Na2O 0.14*
TiO2 0.00
Al2O3 0.35
B2O3 0.21
P2O5 0.00
SiO2 3.35
Si:Al 9.65
SiB:Al 10.27
Expan 7.03
I thought at first it was the small amount of barium in the 5Cl that was
causing the grey stains to go pink. Until I tried them in the SC40F.
By
the way, there is no opacifier of any kind, much less tin oxide, in any
of
these. And this color response will happen if samples of all three are
side
by side in the same firing, so it's not temperature, cooling rate, or
stuff
volatilizing. It's not Si:Al ratio, as the one that stays grey is the
one
in the middle for ratio. Except for the barium in the 5CL, they all
have
the same oxides in different proportions. The 5x20 has marginally more
CaO
than the SC40F and marginally more Al2O3 than the 5CL. The only thing
it's
got significantly more of than either of the others is the SiO2.
Could that be it? If so, can anyone explain to me why that's making the
difference? Anybody else want to venture a guess?
Paul Lewing, Seattle
________________________________________________________________________
______
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.
June Perry on tue 24 jun 03
The one glaze has magnesia and magnesia combined with tin and cobalt is a
good way to get pink. The stain may have tin and cobalt.
I don't think it's a chrome tin reaction from the stain because both glazes
are high in calcium, no zinc, etc.
I'd be interested in others possible takes on it.
Regards,
June Perry
http://www.angelfire.com/art2/shambhalapottery/index.html
John Britt on tue 24 jun 03
Paul,
How about the Mg?
John Britt
Liisa Reid on tue 24 jun 03
Paul,
The main difference I notice is the dolomite (magnesium). I think, if there's any
cobalt in the grey stain, that might be the culprit.
Curious, Liisa
Paul Lewing wrote:
> OK, Guys, if Clayart's gotten a bit boring for you, I have an old-fashioned
> glaze mystery for you. I use a number of different base glazes and color
> them with various stuff. Recently I've been testing some grey Mason stains
> in three different (but not THAT different) cone 5 oxidation base glazes.
> In two of them the chrome-based grey stains all consistently come out some
> pink or lavender shade and in the other they come out grey. I don't see
> that much difference among them and I'm wondering if any of you can spot
> what's making the difference.
> Here are the two in which grey stains always come out pink.
>
> Two Recipes: 5CL & SC40F
> ========================
> CUSTER FELDSPAR.......... 26.10 22.30
> FLINT.................... 25.20 22.30
> EP KAOLIN................ 14.00 9.90
> FRIT 3134................ 14.00 28.00
> WHITING.................. 10.20 11.80
> DOLOMITE................. 5.60 3.60
> BARIUM CARBONATE......... 4.60
> BENTONITE................ 2.10
> ========= =========
> 99.70 100.00
>
> BaO 0.07*
> CaO 0.63* 0.71*
> MgO 0.10* 0.06*
> K2O 0.09* 0.07*
> Na2O 0.11* 0.16*
> TiO2 0.00 0.00
> Al2O3 0.30 0.22
> B2O3 0.15 0.26
> P2O5 0.00 0.00
> SiO2 2.84 2.57
>
> Si:Al 9.41 11.62
> SiB:Al 9.89 12.80
> Expan 7.40 7.65
>
> Here is the recipe in which the grey stains all come out grey:
>
> 5 X 20
> ====================================
> CUSTER FELDSPAR.......... 20.00
> FRIT 3134................ 20.00
> WOLLASTONITE............. 20.00
> EPK KAOLIN............... 20.00
> SILICA................... 20.00
> =========
> 100.00
>
> CaO 0.79*
> MgO 0.00*
> K2O 0.07*
> Na2O 0.14*
> TiO2 0.00
> Al2O3 0.35
> B2O3 0.21
> P2O5 0.00
> SiO2 3.35
>
> Si:Al 9.65
> SiB:Al 10.27
> Expan 7.03
>
> I thought at first it was the small amount of barium in the 5Cl that was
> causing the grey stains to go pink. Until I tried them in the SC40F. By
> the way, there is no opacifier of any kind, much less tin oxide, in any of
> these. And this color response will happen if samples of all three are side
> by side in the same firing, so it's not temperature, cooling rate, or stuff
> volatilizing. It's not Si:Al ratio, as the one that stays grey is the one
> in the middle for ratio. Except for the barium in the 5CL, they all have
> the same oxides in different proportions. The 5x20 has marginally more CaO
> than the SC40F and marginally more Al2O3 than the 5CL. The only thing it's
> got significantly more of than either of the others is the SiO2.
> Could that be it? If so, can anyone explain to me why that's making the
> difference? Anybody else want to venture a guess?
>
> Paul Lewing, Seattle
>
> ______________________________________________________________________________
> 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.
John Hesselberth on tue 24 jun 03
Hi Paul,
Well, I will take a guess. Nearly all of Mason's "grey" stains that
contain chromium also contain cobalt. The two glazes that go pink on
you have magnesium; the third glaze does not. Magnesium + cobalt in the
presence of alkais can sometimes give purple according to Hamer and
Hamer. That could be where the red is coming from.
Regards,
John
On Tuesday, June 24, 2003, at 01:47 AM, Paul Lewing wrote:
> OK, Guys, if Clayart's gotten a bit boring for you, I have an
> old-fashioned
> glaze mystery for you. I use a number of different base glazes and
> color
> them with various stuff. Recently I've been testing some grey Mason
> stains
> in three different (but not THAT different) cone 5 oxidation base
> glazes.
> In two of them the chrome-based grey stains all consistently come out
> some
> pink or lavender shade and in the other they come out grey. I don't
> see
> that much difference among them and I'm wondering if any of you can
> spot
> what's making the difference.
> Here are the two in which grey stains always come out pink.
>
> Two Recipes: 5CL & SC40F
> ========================
> CUSTER FELDSPAR.......... 26.10 22.30
> FLINT.................... 25.20 22.30
> EP KAOLIN................ 14.00 9.90
> FRIT 3134................ 14.00 28.00
> WHITING.................. 10.20 11.80
> DOLOMITE................. 5.60 3.60
> BARIUM CARBONATE......... 4.60
> BENTONITE................ 2.10
> ========= =========
> 99.70 100.00
>
> BaO 0.07*
> CaO 0.63* 0.71*
> MgO 0.10* 0.06*
> K2O 0.09* 0.07*
> Na2O 0.11* 0.16*
> TiO2 0.00 0.00
> Al2O3 0.30 0.22
> B2O3 0.15 0.26
> P2O5 0.00 0.00
> SiO2 2.84 2.57
>
> Si:Al 9.41 11.62
> SiB:Al 9.89 12.80
> Expan 7.40 7.65
>
>
> Here is the recipe in which the grey stains all come out grey:
>
> 5 X 20
> ====================================
> CUSTER FELDSPAR.......... 20.00
> FRIT 3134................ 20.00
> WOLLASTONITE............. 20.00
> EPK KAOLIN............... 20.00
> SILICA................... 20.00
> =========
> 100.00
>
> CaO 0.79*
> MgO 0.00*
> K2O 0.07*
> Na2O 0.14*
> TiO2 0.00
> Al2O3 0.35
> B2O3 0.21
> P2O5 0.00
> SiO2 3.35
>
> Si:Al 9.65
> SiB:Al 10.27
> Expan 7.03
>
> I thought at first it was the small amount of barium in the 5Cl that
> was
> causing the grey stains to go pink. Until I tried them in the SC40F.
> By
> the way, there is no opacifier of any kind, much less tin oxide, in
> any of
> these. And this color response will happen if samples of all three
> are side
> by side in the same firing, so it's not temperature, cooling rate, or
> stuff
> volatilizing. It's not Si:Al ratio, as the one that stays grey is the
> one
> in the middle for ratio. Except for the barium in the 5CL, they all
> have
> the same oxides in different proportions. The 5x20 has marginally
> more CaO
> than the SC40F and marginally more Al2O3 than the 5CL. The only thing
> it's
> got significantly more of than either of the others is the SiO2.
> Could that be it? If so, can anyone explain to me why that's making
> the
> difference? Anybody else want to venture a guess?
>
http://www.frogpondpottery.com
http://www.masteringglazes.com
John Post on tue 24 jun 03
Hi Paul,
I think that the reason your glaze turns grey in that one base is because of
the increased silica in that glaze(nearly half a mole greater than the other
two).
Do the grey stains you are using contain Nickel? (You didn't mention which
specific stains you were using in your post.) Nickel can make a glaze
appear pink if the alumina and silica levels are low in the glaze. With
higher levels of silica the glaze turns blue-grey.
I ran some Ian Currie line blends looking for Nickel Pink glazes. They
appeared in corner C, the low alumina and low silica corner. There were
about 3 or 4 glazes in the grid that were pink and then the color would
abruptly shift to blue-grey as the silica increased.
I have the grid stored with my test tiles and could send you a scan of it if
you're interested.
Cheers,
John Post
Earl Brunner on tue 24 jun 03
I like John H's answer better, I overlooked the
cobalt, but i think it's still a MgO issue.
--- Earl Brunner wrote:
> Well, you are getting a chrome pink aren't
> you......The big difference I
> see is the MgO.....
>
> -----Original Message-----
> From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On
> Behalf Of Paul Lewing
> Sent: Monday, June 23, 2003 10:48 PM
> To: CLAYART@LSV.CERAMICS.ORG
> Subject: Grey/pink glaze mystery
>
> OK, Guys, if Clayart's gotten a bit boring for you,
> I have an
> old-fashioned
> glaze mystery for you. I use a number of different
> base glazes and
> color
> them with various stuff. Recently I've been testing
> some grey Mason
> stains
> in three different (but not THAT different) cone 5
> oxidation base
> glazes.
> In two of them the chrome-based grey stains all
> consistently come out
> some
> pink or lavender shade and in the other they come
> out grey.
=====
Earl Brunner
e-mail: brunv53@yahoo.com
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