douglas fur on tue 15 dec 09
Janet
It seems like your choice in moving towards dolo. will increase the CaO and
decrease the MgO. The downside is you will lose whatever advantage in
fusibility there is in having the MgO and SiO2 together in the talc.
(anyone out there have any notion how the OH leaving the talc impacts the
melt?)
If your intent is to move from MgO to CaO why not use wollastonite and get
all CaO and keep the advantage of having flux and glass-former in one
mineral?
DRB
Seattle
On Tue, Dec 15, 2009 at 10:04 AM, Janet Moe wrote:
> This is a John Hesselberth Cone 6 glaze that I have used in the past and
> like. It is the base for Xavier's Warm Jade Green. However I would like t=
o
> take the talc out and replace with dolomite for a different colour
> response.
> Any suggestions on this? Thanks
>
>
>
> 40 Custer Feldspar
> 16 Whiting
> 9 Frit 3124
> 9 Talc
> 10 EPK
> 16 Kaolin
>
>
> Janet, on snowy Vancouver Island
>
Janet Moe on tue 15 dec 09
This is a John Hesselberth Cone 6 glaze that I have used in the past and
like. It is the base for Xavier's Warm Jade Green. However I would like to
take the talc out and replace with dolomite for a different colour response=
.
Any suggestions on this? Thanks
40 Custer Feldspar
16 Whiting
9 Frit 3124
9 Talc
10 EPK
16 Kaolin
Janet, on snowy Vancouver Island
Janet Moe on wed 16 dec 09
Ooops, sorry about that, it must be the pre-Christmas fuzzy brain syndrome.
The real recipe is:
40 Custer Feldspar
16 Whiting
9 Frit 3124
9 Talc
10 EPK
16 Silica
I am not trying to get a particular colour. My purpose in doing this is not
to get rid of the MgO but rather it was to compare dolomite and talc and
their effects on colour, just for my own curiosity. I am testing different
colourants in the glaze, although I am particularly interested in the effec=
t
on cobalt. Thanks for your interest.
Janet
On Wed, Dec 16, 2009 at 9:58 PM, wrote:
> Hi Janet,
>
> You have kaolin listed twice - what is the real recipe?
>
> Do you want to remove the MgO (talc is silica and MgO) entirely? What is
> the colour now and what do you want it to be?
>
> RR
>
>
>
> Quoting Janet Moe :
>
> This is a John Hesselberth Cone 6 glaze that I have used in the past and
>> like. It is the base for Xavier's Warm Jade Green. However I would like =
to
>> take the talc out and replace with dolomite for a different colour
>> response.
>> Any suggestions on this? Thanks
>>
>>
>>
>> 40 Custer Feldspar
>> 16 Whiting
>> 9 Frit 3124
>> 9 Talc
>> 10 EPK
>> 16 Kaolin
>>
>>
>> Janet, on snowy Vancouver Island
>>
>>
>
>
>
heidy on wed 16 dec 09
Hi Janet,
I would do it the following way:
NEW RECIPE
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
Cone 6=3D091222 deg.C. - =3D09=3D09
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
Frit 90167 =3D3D 3124 =3D09 6.92
Custer Feldspar=3D0927.72
EPK Kaolin=3D0914.94
Dolomite=3D0914.16
Whiting=3D09 9.99
Silica=3D0926.27
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
=3D09=3D09=3D09=3D09Seger
KNO=3D09 0.214=3D09 6.48%
CaO=3D09 0.587=3D0912.25%
MgO=3D09 0.199=3D09 2.99%
Al2O3=3D09 0.336=3D0912.76%
B2O3=3D09 0.053=3D09 1.36%
SiO2=3D09 2.867=3D0964.12%
TiO2=3D09 0.002=3D09 0.04%
K2O=3D09 0.132=3D09 4.52%
Na2O=3D09 0.082=3D09 1.96%
Al:Si=3D09 8.52=3D09
Expan.=3D09 7.03=3D09
ST=3D09 369.35=3D09
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
regards,
heidy
Paul Lewing on wed 16 dec 09
On Dec 15, 2009, at 10:04 AM, Janet Moe wrote:
This is a John Hesselberth Cone 6 glaze that I have used in the past and
like. It is the base for Xavier's Warm Jade Green. However I would
like to
take the talc out and replace with dolomite for a different colour
response.
One thing that will happen is that you will lose some silica from the
talc, so the glaze may not be as glossy or as stable. You'd have to
compensate for that by adding additional silica. To know just how
much to add to keep the same total amount of silica, you should use a
calculation program.
Taking out the Mg and replacing it with Ca will give you a slightly
more active melt, but for most colorants the color response would not
be that different. The most dramatic would be that without the Mg
cobalt will not give a lavender color. You might get a more
pronounced color shift by substituting one of the other alkaline
earths such as strontium or barium for the Mg. Of course, neither of
these comes as a silicate either, so you'd still have to add silica.
Paul Lewing
www.paullewingtile.com
www.paullewingart.com
Ron Roy on thu 17 dec 09
Hi Janet,
You have kaolin listed twice - what is the real recipe?
Do you want to remove the MgO (talc is silica and MgO) entirely? What
is the colour now and what do you want it to be?
RR
Quoting Janet Moe :
> This is a John Hesselberth Cone 6 glaze that I have used in the past and
> like. It is the base for Xavier's Warm Jade Green. However I would like t=
o
> take the talc out and replace with dolomite for a different colour respon=
se.
> Any suggestions on this? Thanks
>
>
>
> 40 Custer Feldspar
> 16 Whiting
> 9 Frit 3124
> 9 Talc
> 10 EPK
> 16 Kaolin
>
>
> Janet, on snowy Vancouver Island
>
Marcia Selsor on thu 17 dec 09
Janet,
The MgO is in Talc and Dolomite and effects cobalt by going towards a =3D
lavendar blue.=3D20
Marcia=3D20
Marcia Selsor
http://www.marciaselsor.com
On Dec 17, 2009, at 1:04 AM, Janet Moe wrote:
> Ooops, sorry about that, it must be the pre-Christmas fuzzy brain =3D
syndrome.
> The real recipe is:
>=3D20
> 40 Custer Feldspar
> 16 Whiting
> 9 Frit 3124
> 9 Talc
> 10 EPK
> 16 Silica
>=3D20
> I am not trying to get a particular colour. My purpose in doing this =3D
is not
> to get rid of the MgO but rather it was to compare dolomite and talc =3D
and
> their effects on colour, just for my own curiosity. I am testing =3D
different
> colourants in the glaze, although I am particularly interested in the =3D
effect
> on cobalt. Thanks for your interest.
>=3D20
> Janet
>=3D20
> On Wed, Dec 16, 2009 at 9:58 PM, wrote:
>=3D20
>> Hi Janet,
>>=3D20
>> You have kaolin listed twice - what is the real recipe?
>>=3D20
>> Do you want to remove the MgO (talc is silica and MgO) entirely? What =
=3D
is
>> the colour now and what do you want it to be?
>>=3D20
>> RR
>>=3D20
>>=3D20
>>=3D20
>> Quoting Janet Moe :
>>=3D20
>> This is a John Hesselberth Cone 6 glaze that I have used in the past =3D
and
>>> like. It is the base for Xavier's Warm Jade Green. However I would =3D
like to
>>> take the talc out and replace with dolomite for a different colour
>>> response.
>>> Any suggestions on this? Thanks
>>>=3D20
>>>=3D20
>>>=3D20
>>> 40 Custer Feldspar
>>> 16 Whiting
>>> 9 Frit 3124
>>> 9 Talc
>>> 10 EPK
>>> 16 Kaolin
>>>=3D20
>>>=3D20
>>> Janet, on snowy Vancouver Island
>>>=3D20
>>>=3D20
>>=3D20
>>=3D20
>>=3D20
>=3D20
Ron Roy on thu 17 dec 09
Hi Janet,
Here is that glaze with dolomite subbed in for talc and adjusted so
that all the oxides are the same. The ratio of silica to alumina is
the same and the expansion is also very close.
39.20 CUSTER SPAR
9.30 WHITING
8.80 F3124
12.70 DOLOMITE
9.80 EPK
20.10 SILICA
0.58* CaO
0.20* MgO
0.13* K2O
0.09* Na2O
0.00 Fe2O3
0.00 TiO2
0.05 B2O3
0.34 Al2O3
2.90 SiO2
0.00 P2O5
Calculated LOI: 11.47
Si:Al: 8.48
SiB:Al: 8.64
Thermal Expansion: 512.74
Formula Weight: 272.06
If you simply sub dolomite for talc you get the following - more
calcium, less magnesium, less alumina and silica - making it less
durable and raising the expansion so it may now craze. The
silica/alumina ratio is lower so it will probably be less shiny.
You must do a 500 gram test to be sure they will work OK - do tell us
what happens.
40.00 CUSTER SPAR
16.00 WHITING
9.00 F3124
9.00 DOLOMITE
10.00 EPK
16.00 SILICA
0.66* CaO
0.14* MgO
0.12* K2O
0.08* Na2O
0.00 Fe2O3
0.00 TiO2
0.05 B2O3
0.32 Al2O3
2.51 SiO2
0.00 P2O5
Calculated LOI: 12.78more calcium, less
Si:Al: 7.84
SiB:Al: 7.99
Thermal Expansion: 567.08
Formula Weight: 246.86
RR
Quoting Janet Moe :
> Ooops, sorry about that, it must be the pre-Christmas fuzzy brain syndrom=
e.
> The real recipe is:
>
> 40 Custer Feldspar
> 16 Whiting
> 9 Frit 3124
> 9 Talc
> 10 EPK
> 16 Silica
>
>
> I am not trying to get a particular colour. My purpose in doing this is n=
ot
> to get rid of the MgO but rather it was to compare dolomite and talc and
> their effects on colour, just for my own curiosity. I am testing differen=
t
> colourants in the glaze, although I am particularly interested in the eff=
ect
> on cobalt. Thanks for your interest!
>
> Janet
>
> On Wed, Dec 16, 2009 at 9:58 PM, wrote:
>
>> Hi Janet,
>>
>> You have kaolin listed twice - what is the real recipe?
>>
>> Do you want to remove the MgO (talc is silica and MgO) entirely? What is
>> the colour now and what do you want it to be?
>>
>> RR
>>
>>
>>
>> Quoting Janet Moe :
>>
>> This is a John Hesselberth Cone 6 glaze that I have used in the past an=
d
>>> like. It is the base for Xavier's Warm Jade Green. However I would like=
to
>>> take the talc out and replace with dolomite for a different colour
>>> response.
>>> Any suggestions on this? Thanks
>>>
>>>
>>>
>>> 40 Custer Feldspar
>>> 16 Whiting
>>> 9 Frit 3124
>>> 9 Talc
>>> 10 EPK
>>> 16 Kaolin
>>>
>>>
>>> Janet, on snowy Vancouver Island
>>>
>>>
>>
>>
>>
>
Edouard Bastarache on thu 17 dec 09
Maybe you could use a mixture of
Silica and Magnesium Carb.
Gis,
Edouard Bastarache
Spertesperantisto
Sorel-Tracy
Quebec
http://edouardbastarache.blogspot.com/
http://www.flickr.com/photos/30058682@N00/
http://cerampeintures.blogspot.com/
http://albertpaintings.blogspot.com/
John Hesselberth on fri 18 dec 09
> On Dec 15, 2009, at 10:04 AM, Janet Moe wrote:
>=3D20
> This is a John Hesselberth Cone 6 glaze that I have used in the past =3D
and
> like. It is the base for Xavier's Warm Jade Green. However I would
> like to
> take the talc out and replace with dolomite for a different colour
> response.
Hi Janet,
First to give credit where it is due, this is a glaze from Cushing's =3D
Handbook that has been quite popular over the years. It is on my web =3D
site because it has been leach tested a number of times and has shown =3D
itself it be quite stable. Stable medium/dark green glazes colored by =3D
copper carbonate are few and far between.
Anyhow with your particular request I would replace the talc one for one =
=3D
with wollastonite. This will keep the silica level close to the same =3D
while replacing magnesium with calcium. That is a logical replacement =3D
since they are both alkaline earths. When you do that you will move =3D
toward the composition of the high calcium semimatte glazes that are in =3D
MC6Gs so you might try one of those for comparison.
Regards,
John
Marcia Selsor on fri 18 dec 09
John,
Remind me if this is correct. Calcium makes a glaze surface less =3D
vulnerable to scratches from silverware (flatware).
This would be one reason to swich from MgO to CaO.
Just curious if my memory is working.
Marcia=3D20
On Dec 18, 2009, at 5:48 AM, John Hesselberth wrote:
>> On Dec 15, 2009, at 10:04 AM, Janet Moe wrote:
>>=3D20
>> This is a John Hesselberth Cone 6 glaze that I have used in the past =3D
and
>> like. It is the base for Xavier's Warm Jade Green. However I would
>> like to
>> take the talc out and replace with dolomite for a different colour
>> response.
>=3D20
> Hi Janet,
>=3D20
> First to give credit where it is due, this is a glaze from Cushing's =3D
Handbook that has been quite popular over the years. It is on my web =3D
site because it has been leach tested a number of times and has shown =3D
itself it be quite stable. Stable medium/dark green glazes colored by =3D
copper carbonate are few and far between.
>=3D20
> Anyhow with your particular request I would replace the talc one for =3D
one with wollastonite. This will keep the silica level close to the same =
=3D
while replacing magnesium with calcium. That is a logical replacement =3D
since they are both alkaline earths. When you do that you will move =3D
toward the composition of the high calcium semimatte glazes that are in =3D
MC6Gs so you might try one of those for comparison.
>=3D20
> Regards,
>=3D20
> John
>=3D20
Marcia Selsor
http://www.marciaselsor.com
John Hesselberth on fri 18 dec 09
Hi Marcia,
Well........... I think the main reason to switch would be color =3D
response and/or surface aesthetics. A second reason might be to get =3D
slightly better melting and, therefore, 'better glass' if you were on =3D
the edge of not fully melting. I guess that might give better 'scratch =3D
resistance' or a less rough surface which would result in less metal =3D
marking. I put scratch resistance in quotes because silverware doesn't =3D
scratch ceramic glazes--it is the other way around--ceramic =3D
glazes--particularly matte surface-- can abrade metal and leave little =3D
particles of the silverware embedded in the nooks and crannies of the =3D
glazed surface.
Regards,
John
On Dec 18, 2009, at 8:08 AM, Marcia Selsor wrote:
> John,
> Remind me if this is correct. Calcium makes a glaze surface less =3D
vulnerable to scratches from silverware (flatware).
> This would be one reason to swich from MgO to CaO.
> Just curious if my memory is working.
> Marcia=3D20
> On Dec 18, 2009, at 5:48 AM, John Hesselberth wrote:
>=3D20
>>> On Dec 15, 2009, at 10:04 AM, Janet Moe wrote:
>>>=3D20
>>> This is a John Hesselberth Cone 6 glaze that I have used in the past =
=3D
and
>>> like. It is the base for Xavier's Warm Jade Green. However I would
>>> like to
>>> take the talc out and replace with dolomite for a different colour
>>> response.
>>=3D20
>> Hi Janet,
>>=3D20
>> First to give credit where it is due, this is a glaze from Cushing's =3D
Handbook that has been quite popular over the years. It is on my web =3D
site because it has been leach tested a number of times and has shown =3D
itself it be quite stable. Stable medium/dark green glazes colored by =3D
copper carbonate are few and far between.
>>=3D20
>> Anyhow with your particular request I would replace the talc one for =3D
one with wollastonite. This will keep the silica level close to the same =
=3D
while replacing magnesium with calcium. That is a logical replacement =3D
since they are both alkaline earths. When you do that you will move =3D
toward the composition of the high calcium semimatte glazes that are in =3D
MC6Gs so you might try one of those for comparison.
>>=3D20
>> Regards,
>>=3D20
>> John
>>=3D20
>=3D20
> Marcia Selsor
> http://www.marciaselsor.com
>=3D20
>=3D20
>=3D20
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