Craig Martell on sun 1 mar 98
At 11:36 AM 2/28/98 EST, Brad wrote:
>----------------------------Original message----------------------------
>So here's a black glaze I've just developed, and I hereby throw to the
>sharks:
>
>H38-40 Sondahl Black Gloss Cone 8-10 oxidation
>Dolomite 8.5
>Custer feldspar 23.3
>Nepheline syenite 8.8
>Kaolin 13.7
>Flint 16.2
>Kona F-4 Spar 16.7
>Wollastonite 6.7
>Bone ash 1.5
>Whiting 4.7
>
>Colorants
>Red iron oxide 1.5
>Cobalt carbonate 2.3
>Copper carbonate 2.3
>
>It's probably unnecessarily complicated because it's a hybrid of two
>other glazes.
Great, a few posts back it was the "glaze police", now it's "sharks", what next?
The glaze looks OK in terms of limits and the colorants don't appear to be
in the high range. I would be tempted to raise the silica a bit more
though. It's just above the low limit now. You may want to simplify this
glaze against the Seger Formula and cut down your mixing time and the number
of ingredients. For instance, you can up the wollastonite, which will add
more silica and calcium so you could drop the whiting. You could raise the
soda spar and dump the neph sy etc etc. Anyway, here's the calculation below.
I gotta go polish my fin and hit the water. I hear that there are a lot of
bathers about today and I'm gonna go bite some ankles.....Craig Martell-Oregon
Untitled Recipe 1
CUSTER FELDSPAR 23.30 CaO 0.57*
DOLOMITE 8.50 MgO 0.16*
NEPHELINE SYENITE 8.80 K2O 0.13*
KONA F-4 FELDSPAR 16.70 Na2O 0.15*
WOLLASTONITE 6.70 Fe2O3 0.00
WHITING 4.70 TiO2 0.00
BONE ASH 1.50 P2O5 0.02
EPK KAOLIN 13.70 Al2O3 0.47
SILICA 16.20 SiO2 3.23
========
100.10
Cost/kg 0.18
Si:Al 6.86
SiB:Al 6.86
Expan 7.31
Lili Krakowski on mon 2 mar 98
I forgot which of our generous industrial hygienist CLAYARTERS donated the
information that while definitely, some metals are
desirable in the diet, the amounts are teensy-tiny, as labels on mineral
supplements tell us. Excessive amounts can be dangerous--though I do not
know what they are or where they begin. I DO KNOW that the child of a
friend had to be rushed to the ER in mortal danger because it had guzzled
down a botle full of children's vitamin/minerals (probably no more than
100, probably less)! Apparently extra iron is extremely
bad for kids--but I am not a toxicologist, nor a pediatrician and I could
not tell you what the amounts are. Suffice it to say that if a lot of
color is used,to produce black and the glaze leaches we cannot just say ah
well. What of the
person who leaves coleslaw in a black bowl overnight? Or the person who
"always " has a cup fo black coffee in a black cup at her elbow, or a
black goblet of red wine beside him as he watches TV all evening.
Prevention is much better than cure, Brad; and risk taking is just that.
Lili Krakowski
Veena Raghavan on tue 9 feb 99
Appeal to fellow Clayarters,
I tried to post this a few days ago, but I don't think it made it,
in hope, I am posting it again. If anyone would be kind enough to either
share a foodsafe black or can tell me where I could find one in a book, I
would be very grateful. The black we use in our studio is very unreliable,
and since black is something I like to use often, I am confined to using
the blacks I have mixed up myself, which I understand are not food safe, on
non functional items.
If anyone can help, I would really appreciate it.
Thanks in advance.
Veena
Veena Raghavan
75124.2520@compuserve.com
Dale A. Neese on wed 10 feb 99
For inquires about glazes or glaze problems it would be helpful to us all to
include the firing temperature.
thanks,
Dale Tex
-----Original Message-----
From: Veena Raghavan <75124.2520@compuserve.com>
To: CLAYART@LSV.UKY.EDU
Date: Tuesday, February 09, 1999 6:41 AM
Subject: Foodsafe Black
>----------------------------Original message----------------------------
>Appeal to fellow Clayarters,
> I tried to post this a few days ago, but I don't think it made it,
>in hope, I am posting it again. If anyone would be kind enough to either
>share a foodsafe black or can tell me where I could find one in a book, I
>would be very grateful. The black we use in our studio is very unreliable,
>and since black is something I like to use often, I am confined to using
>the blacks I have mixed up myself, which I understand are not food safe, on
>non functional items.
> If anyone can help, I would really appreciate it.
>Thanks in advance.
>Veena
>Veena Raghavan
>75124.2520@compuserve.com
>
Veena Raghavan on thu 11 feb 99
Mea Culpa fellow Clayarters,
I apologize for not having included the cone in my request for a
foodsafe black. It was an unintential ommission. Sorry for any confusion
and wasted time. It is Cone 6 oxidation.
Veena
Veena Raghavan
75124.2520@compuserve.com
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