Daraburn@AOL.COM on thu 4 apr 02
OK, here I sit at the computer, Ron & John's book open, and warm pots from
the kiln. Got a glaze I sorta like but when I put the recipe in Insight I'm
not sure it meets the standards for durability etc. I'm really new at this,
hate math and numbers with a passion, but paranoid about glaze safety. This
glaze is Honey Amber from Don Goodrich's site, cone 6 ox. I am looking for a
clear transparent glaze that looks like thin honey or syrup poured over.
This looks like that, but is it stable? If not can you help me "fix" it?
Thanks! Dawn
=================
Honey Amber cone 6 ox.
dolomite............ 20.00 17.39%
3134................ 20.00 17.39%
spodumene........... 20.00 17.39%
om4................. 20.00 17.39%
flint............... 25.00 21.74%
bentonite........... 2.00 1.74%
manganese........... 3.00 2.61%
*red iron oxide...... 5.00 4.35%
========
115.00
CaO 0.46* 11.51%w 12.52%m
Li2O 0.12* 1.58%w 3.24%m
MgO 0.26* 4.69%w 7.10%m
K2O 0.01* 0.29%w 0.19%m
Na2O 0.08* 2.27%w 2.24%m
TiO2 0.01 0.25%w 0.19%m
Al2O3 0.25 11.64%w 6.97%m
B2O3 0.15 4.80%w 4.21%m
SiO2 2.22 60.10%w 61.04%m
Fe2O3 0.00 0.32%w 0.12%m
MnO 0.08* 2.54%w 2.19%m
Cost/kg 1.21
Si:Al 8.76
SiB:Al 9.37
Expan 6.10
Paul Lewing on thu 4 apr 02
Dawn,
without having this tested you can't say conclusively whether this will
leach or not. But with just a quick glance, I'd say it's a bit low in both
Al2O3 and SiO2. What I'd do is increase both the ball clay and the silica
till the Al2O3 gets up around .3, and keep the Si:Al ratio the same. If
that makes the glaze turn out a bit more matte, you might substitute whiting
for some or all of the dolomite.
And a word about your hating math. This is not math. This is just
comparing numbers. You're obviously using Insight, and it's doing the math
for you. Try not to think of looking at glaze formulas as math; try to
think of it as just learning to compare sets of numbers. Think of all the
sets of numbers you are intimately familiar with in your daily life, in
cars, computers, food recipes, prices, distances, and so on. This is no
harder, it just takes time, and paying attention for a while. As I always
say, there are three kinds of people in the world- those who understand
numbers and those who don''t.
Paul Lewing, Seattle
John Hesselberth on thu 4 apr 02
Hi Dawn,
I'm glad to see you are beginning to work with unity formula--after a while
it will come a lot easier.
This glaze is a little lower in silica than I like to see. It is also on
the bottom edge of alumina level. It would definitely not be a good general
purpose base glaze. On the other hand 3% manganese and 5% RIO are pretty
easy to keep in a glaze. I would guess this glaze is fairly stable, but
only testing will tell for sure. At least vinegar test it. You certainly
would want glazes that wouldn't fade after being exposed to vinegar. If you
leach test it, you might test for lithium and manganese.
If I were to try to improve it I would add a little more clay to get alumina
up to .30 Then I would top if off with silica--try to get it up to between
2.5 and 3.0. Then you'd have a better glaze and it will probably look about
the same. When I made those changes I'd do a line blend with your
original--you may have a little trouble getting the glaze I talked about
above to melt; however something half way inbetween might be a better overal
compromise.
Have fun,
John
on 4/4/02 1:19 PM, Daraburn@AOL.COM at Daraburn@AOL.COM wrote:
> OK, here I sit at the computer, Ron & John's book open, and warm pots from
> the kiln. Got a glaze I sorta like but when I put the recipe in Insight I'm
> not sure it meets the standards for durability etc. I'm really new at this,
> hate math and numbers with a passion, but paranoid about glaze safety. This
> glaze is Honey Amber from Don Goodrich's site, cone 6 ox. I am looking for a
> clear transparent glaze that looks like thin honey or syrup poured over.
> This looks like that, but is it stable? If not can you help me "fix" it?
> Thanks! Dawn
> =================
> Honey Amber cone 6 ox.
> dolomite............ 20.00 17.39%
> 3134................ 20.00 17.39%
> spodumene........... 20.00 17.39%
> om4................. 20.00 17.39%
> flint............... 25.00 21.74%
> bentonite........... 2.00 1.74%
> manganese........... 3.00 2.61%
> *red iron oxide...... 5.00 4.35%
> ========
> 115.00
>
> CaO 0.46* 11.51%w 12.52%m
> Li2O 0.12* 1.58%w 3.24%m
> MgO 0.26* 4.69%w 7.10%m
> K2O 0.01* 0.29%w 0.19%m
> Na2O 0.08* 2.27%w 2.24%m
> TiO2 0.01 0.25%w 0.19%m
> Al2O3 0.25 11.64%w 6.97%m
> B2O3 0.15 4.80%w 4.21%m
> SiO2 2.22 60.10%w 61.04%m
> Fe2O3 0.00 0.32%w 0.12%m
> MnO 0.08* 2.54%w 2.19%m
>
> Cost/kg 1.21
> Si:Al 8.76
> SiB:Al 9.37
> Expan 6.10
>
web sites: http://www.masteringglazes.com and http://www.frogpondpottery.com
EMail: john@frogpondpottery.com
"It is, perhaps, still necessary to say that the very best glazes cannot
conceal badly shaped pots..." David Green, Pottery Glazes
Ron Roy on sat 6 apr 02
Hi Dawn,
Looks good enough to me the way it is except for the low expansion - sub in
10 G200 or Custer and take out 10 spod - if it wants to slide a bit just
start increasing the clay (OM#4) till it stops - that will help the
durability at the same time.
When I calculate this glaze I get better silica (2.63) and alumina (0.29)
than you do but I can't figure out why yours is so short. I also notice
your fluxes don't add up to 1.0 - only 0.93 - wait I see why - you have MnO
(should be MnO2) included in with the fluxes - take it out of unity. When I
put MnO2 in unity our numbers are much closer. It's easy to adjust whats in
and out of unity with Insight - if you need to know how just email me.
I would recommend doing the lemon test for 2 or 3 days and take a good look
with a magnifier to see if it changes. If it does send it to me and I will
fix it.
You may also be able to get along without some of that manganese - just sub
in iron for what you take out.
This is not the kind of glaze you need to be concerned about - leaching is
going to be minimal at worst.
RR
>OK, here I sit at the computer, Ron & John's book open, and warm pots from
>the kiln. Got a glaze I sorta like but when I put the recipe in Insight I'm
>not sure it meets the standards for durability etc. I'm really new at this,
>hate math and numbers with a passion, but paranoid about glaze safety. This
>glaze is Honey Amber from Don Goodrich's site, cone 6 ox. I am looking for a
>clear transparent glaze that looks like thin honey or syrup poured over.
>This looks like that, but is it stable? If not can you help me "fix" it?
>Thanks! Dawn
>=================
> Honey Amber cone 6 ox.
>dolomite............ 20.00 17.39%
> 3134................ 20.00 17.39%
> spodumene........... 20.00 17.39%
> om4................. 20.00 17.39%
> flint............... 25.00 21.74%
> bentonite........... 2.00 1.74%
> manganese........... 3.00 2.61%
>*red iron oxide...... 5.00 4.35%
> ========
> 115.00
>
> CaO 0.46* 11.51%w 12.52%m
> Li2O 0.12* 1.58%w 3.24%m
> MgO 0.26* 4.69%w 7.10%m
> K2O 0.01* 0.29%w 0.19%m
> Na2O 0.08* 2.27%w 2.24%m
> TiO2 0.01 0.25%w 0.19%m
> Al2O3 0.25 11.64%w 6.97%m
> B2O3 0.15 4.80%w 4.21%m
> SiO2 2.22 60.10%w 61.04%m
> Fe2O3 0.00 0.32%w 0.12%m
> MnO 0.08* 2.54%w 2.19%m
>
> Cost/kg 1.21
> Si:Al 8.76
> SiB:Al 9.37
> Expan 6.10
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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