douglas gray on thu 8 jan 98
June the glaze recipe I have has the kaolin and whiting switched. Looks like...
cone 9-10 reduction
40 Custer feldspar
30 Flint
20 Whiting
10 Kaolin
I use this same base for a saturated iron. The addtion of iron ox. makes it
fluid though so I up the kaolin to 20. This recipe looks like...
Saturated Iron
cone 9-10 reduction
40 Custer Feldspar
30 flint
20 whiting
20 kaolin
10 red iron ox.
Just to get even more variation from this glaze, use a bone ash and water
solution (enough to make a good paintable consistency) brushed over glaze to
make the saterated iron surface go brick red. Rutile, gerstley borate and water
mixture makes it go metalic bronze/gold.
doug
In message GURUSHAKTI writes:
> ----------------------------Original message----------------------------
> The 25,25,25,25 glaze is the old cone 9 Leach white glaze.
>
> The 1234 glaze is if I remember, correctly, is:
>
> 40 Feldspar
> 30 Flint
> 20 Kaolin
> 10 Whiting
>
> Now that I wrote it out I'm thinking that the kaolin and whiting may be
> reversed????Anyone out there remember this one?
>
> Regards,
============================================================================ =)
Douglas E. Gray, Assistant Professor of Art
P.O. Box 100547
Department of Fine Arts and Mass Communication
Francis Marion Univeristy
Florence, South Carolina 29501-0547
dgray@fmarion.edu
803/661-1535
Cindy on fri 9 jan 98
Doug and others,
I'm trying to understand the glaze chemistry thing. This glaze is high both
in silica and in alumina (more so in alumina, and especially the RIO
version) according to the limits given in Insight for a ^8-10 glaze. I know
low is bad with silica, but since they're both high, is that acceptable?
What is the correct range for the silica/alumina ratio for a ^8-10 glaze?
For a ^6 glaze? I've looked in Magic of Fire and (though it's probably
there somewhere) I can't seem to find it.
Thanks for the help,
Cindy in Custer, SD
> June the glaze recipe I have has the kaolin and whiting switched. Looks
like...
>
> cone 9-10 reduction
>
> 40 Custer feldspar
> 30 Flint
> 20 Whiting
> 10 Kaolin
>
> I use this same base for a saturated iron. The addtion of iron ox.
makes it
> fluid though so I up the kaolin to 20. This recipe looks like...
>
> Saturated Iron
> cone 9-10 reduction
> 40 Custer Feldspar
> 30 flint
> 20 whiting
> 20 kaolin
>
> 10 red iron ox.
>
> Just to get even more variation from this glaze, use a bone ash and water
> solution (enough to make a good paintable consistency) brushed over glaze
to
> make the saterated iron surface go brick red. Rutile, gerstley borate
and water
> mixture makes it go metalic bronze/gold.
>
> doug
> In message GURUSHAKTI writes:
> > ----------------------------Original
message----------------------------
> > The 25,25,25,25 glaze is the old cone 9 Leach white glaze.
> >
> > The 1234 glaze is if I remember, correctly, is:
> >
> > 40 Feldspar
> > 30 Flint
> > 20 Kaolin
> > 10 Whiting
> >
> > Now that I wrote it out I'm thinking that the kaolin and whiting may be
> > reversed????Anyone out there remember this one?
> >
> > Regards,
>
>
>
============================================================================
=)
> Douglas E. Gray, Assistant Professor of Art
> P.O. Box 100547
> Department of Fine Arts and Mass Communication
> Francis Marion Univeristy
> Florence, South Carolina 29501-0547
>
> dgray@fmarion.edu
> 803/661-1535
Mike Vatalaro on sat 10 jan 98
>----------------------------Original message----------------------------
>Doug and others,
>
>I'm trying to understand the glaze chemistry thing. This glaze is high both
>in silica and in alumina (more so in alumina, and especially the RIO
>version) according to the limits given in Insight for a ^8-10 glaze. I know
>low is bad with silica, but since they're both high, is that acceptable?
>What is the correct range for the silica/alumina ratio for a ^8-10 glaze?
>For a ^6 glaze? I've looked in Magic of Fire and (though it's probably
>there somewhere) I can't seem to find it.
>
>Thanks for the help,
>
>Cindy in Custer, SD
>
>
>> June the glaze recipe I have has the kaolin and whiting switched. Looks
>like...
>>
>> cone 9-10 reduction
>>
>> 40 Custer feldspar
>> 30 Flint
>> 20 Whiting
>> 10 Kaolin
>>
>> I use this same base for a saturated iron. The addtion of iron ox.
>makes it
>> fluid though so I up the kaolin to 20. This recipe looks like...
>>
>> Saturated Iron
>> cone 9-10 reduction
>> 40 Custer Feldspar
>> 30 flint
>> 20 whiting
>> 20 kaolin
>>
>> 10 red iron ox.
>>
>> Just to get even more variation from this glaze, use a bone ash and water
>> solution (enough to make a good paintable consistency) brushed over glaze
>to
>> make the saterated iron surface go brick red. Rutile, gerstley borate
>and water
>> mixture makes it go metalic bronze/gold.
>>
>> doug
>> In message GURUSHAKTI writes:
>> > ----------------------------Original
>message----------------------------
>> > The 25,25,25,25 glaze is the old cone 9 Leach white glaze.
>> >
>> > The 1234 glaze is if I remember, correctly, is:
>> >
>> > 40 Feldspar
>> > 30 Flint
>> > 20 Kaolin
>> > 10 Whiting
>> >
>> > Now that I wrote it out I'm thinking that the kaolin and whiting may be
>> > reversed????Anyone out there remember this one?
>> >
>> > Regards,
>>
>>
>>
>============================================================================
>=)
>> Douglas E. Gray, Assistant Professor of Art
>> P.O. Box 100547
>> Department of Fine Arts and Mass Communication
>> Francis Marion Univeristy
>> Florence, South Carolina 29501-0547
>>
>> dgray@fmarion.edu
>> 803/661-1535
Doug and cindy , We use 1234 as the shop clear cone 10 glaze, the
recipe as Doug listed it is correct ----
for a clear glossy , whats interesting about this formula is that by sub
out you can get several other good results,play with it . 30 clay and 20
flint should produce a satin. the silca to clay retio is most important
for determining surface quality, not really the temp necesarily.
Good luck, Mike Vatalaro
Clemson U
Ron Roy on sat 10 jan 98
Hi Cindy,
Two questions here - one about limits and the other about ratio.
The ratio thing first - there is no such thing as a correct silica /alumina
ratio. Generally speaking below 5 (%parts silica to 1 part alumina)
indicates a matte glaze - 10 to 1 means a glossy glaze and in between the
two - different degrees of semi gloss or semi matte. If you are lowering or
raising the maturing temperature of a glaze and want to keep it looking the
same you try to keep the ratio the same - it does not always work but it's
the first thing you usually try.
when I calculate the second glaze (with 20 EPK) I get silica and alumina
within the limits - do you have the unity on the fluxes - as in the seger
unity formula. Here is the calculation I get-
-----------------
CUSTER SPAR......... 40.00 33.33%
SILICA.............. 30.00 25.00%
WHITING............. 20.00 16.67%
EPK................. 20.00 16.67%
RED IRON OX......... 10.00 8.33%
----------
120.00
FORMULA & ANALYSIS
------------------
*CaO........ .75 10.33%
*MgO........ .01 .07%
*K2O........ .17 3.80%
*Na2O....... .07 1.13%
Fe2O3...... .24 9.48%
TIO2....... .00 .06%
AL2O3...... .53 13.31%
SiO2....... 4.21 61.81%
P2O5....... .00 .02%
RATIO 7.90
EXPAN 512.74
WEIGHT 409.17
I think a more realistic picture would be if you included the iron in with
the fluxes - if this is a reduction fired glaze the Fe2O3 is reduced to FeO
- reduced iron is a heavy duty flux so ---
Untitled Recipe 2
-----------------
CUSTER SPAR......... 40.00 33.33%
SILICA.............. 30.00 25.00%
WHITING............. 20.00 16.67%
EPK................. 20.00 16.67%
RED IRON OX......... 10.00 8.33%
----------
120.00
FORMULA & ANALYSIS
------------------
*CaO........ .61 10.33%
*MgO........ .01 .07%
*K2O........ .13 3.80%
*Na2O....... .06 1.13%
*Fe2O3...... .19 9.48%
TIO2....... .00 .06%
AL2O3...... .43 13.31%
SiO2....... 3.39 61.81%
P2O5....... .00 .02%
RATIO 7.90
EXPAN 512.74
WEIGHT 329.36
The silica and alumina are lower but still within the limits that come with
Insight - and both versions are balanced, and probably, durable glazes at
cone 10 oxidation and reduction.
This all seems simple to me now - is it just because I have been doing it
so long? Whenever I post this kind of stuff the silence is deafening - is
there anyone out there - are my expanations too compicated - It would be
nice to at least get an occasional question - just so I'll know I'm still
alive.
Ron Roy
93 Pegasus Trail
Scarborough,Canada
M1G 3N8
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
Jim and Judith Enright on sun 11 jan 98
Ron -- you and your expertise are mightily appreciated. While I have to
admit that much of your technical ability goes beyond my current limits,
your willingness to explain, and keep explaining, is valued. You, Tom and
Craig keep the essence and importance of glaze calculation alive and I, for
one, am grateful.
-- Judith Enright
Maggie & David on mon 12 jan 98
Dear Ron, I've managed to let over 6,500 messages accumulate due to a most
insane first Christmas season in business and just can't bear to hit the
delete button without at least cursory perusal of them all. Normally, I
scan messages by subject with three exceptions. I read all the messages
that you post, along with Tom B and Craig M. so PLEASE don't stop posting
your wisdom, it is most valuable to many of us. I've just begun the journey
down the road towards glaze calculation and often don't even know enough to
ask any intelligent questions but every post you guys send is another drop
in the bucket for me and I'm eternally grateful. Best wishes for the new
year- Maggie, who's still trying how to figure out how to quit her day job.
ZALT on thu 15 jan 98
Ron;
When I see your handle on the e-mail discussing glaze, I stop and read.
Thank you for your dedication to helping those of us who know just enough
about glaze calculation and analysis to make a great mess inside our kilns.
Your insite has saved me some big problems.
Returning from the Dark Ages. Just got our electricity back on and Oh Boy,
some Heat.
Terrance F. Lazaroff
St-Hubert, Quebec, Canada
| |
|
