Jim and Marge Wade on wed 3 oct 01
Quick question. I have a batch of a clear ^05 glaze that I would like to try
adding some different oxides to. I usually do this when mixing the initial
glaze, but I have about half a gallon already mixed up. Is there any rule of
thumb on adding various oxides to a glaze that is ready to go? For example 1
cup (or perhaps so many grams) of glaze to a certain percent oxide? I recall
reading about it somewhere a while back. Thanks in advance for your help.
Marge
Marianne Lombardo on wed 3 oct 01
Hi Marge,
Yes, there is. Tom Buck explained to me a while ago about using the
Brongniart Formula to calculate the amount of solids in a glaze base
that's already mixed up. Unforunately, I'm not going to be very good
at explaining this to you because I barely understood it myself. If
you search the archives for "Brongniart Formula" I believe you will
find some information about it. I seem to recall a few messages that
explained how it works.
Sorry I can't be more help.
Marianne
> glaze, but I have about half a gallon already mixed up. Is there any
rule of
> thumb on adding various oxides to a glaze that is ready to go? For
example 1
> cup (or perhaps so many grams) of glaze to a certain percent oxide?
I recall
> reading about it somewhere a while back. Thanks in advance for your
help.
Mike Gordon on wed 3 oct 01
Naturally it depends on the color you are trying to achieve.I mix cobalt
carb., copper carb & blk. iron oxide to get three different glaze colors
out of the same base C05 clear glaze.The 3rd color is a mix of cobalt
and copper & blk. iron to get a dark green, sometimes black green or
bluish green.I mix to an eye color and see what comes up, it gives the
students a good variation.If your looking for more predictable colors,
test a gram in a pint, or what ever... Mike Gordon
Ray Gonzalez on thu 4 oct 01
this is the way i have done it. i dont know how right or wrong it is but it
works.
the way i have done it is to essentially weigh the specific gravity. i will
try to explain this but it gets hairy. the only way that this is accurate
is to assume that you weighed it out where you live now. that is to assume
that you have not changed water supply as the amount of garbage (minerals
and 'stuff') would and could drastically change. you will need a gram scale
and a graduated cylinder. you can get a graduated cylinder from triess
sciences in LA. (thats where i get mine because they are local to me.)
about $8 as i recall for a glass one.
weigh out 100 ml. of glaze. record the weight. weigh out 100 ml. of water.
record the weight. subtract the amount of water from the amount of glaze.
this is the amount of raw material in the glaze. you can then weigh out a
large batch and keep this ratio. then add your colorants at 1-10% as you
would do normally. i cant tell you these. i have been testing my 05 lead
base for months to get the desired results. pick up potters pallete. any
glaze book will have info on percentages. i have been using potters pallete
as a guide. none of my tests come out like theirs but it works. something
i had to laugh at is copper oxide black. for so long i have associated it
with red. in reduction, it is a red colorant. i have, in the past always
done reduction. but much to my surprise. it makes green. it was funny.
of course it makes green. its copper i said to myself!
good luck.
ray
if you have any further questions, rayg@hughes.net
----- Original Message -----
From: "Jim and Marge Wade"
To:
Sent: Wednesday, October 03, 2001 6:19 AM
Subject: adding colorants to low fire glaze
> Quick question. I have a batch of a clear ^05 glaze that I would like to
try
> adding some different oxides to. I usually do this when mixing the initial
> glaze, but I have about half a gallon already mixed up. Is there any rule
of
> thumb on adding various oxides to a glaze that is ready to go? For example
1
> cup (or perhaps so many grams) of glaze to a certain percent oxide? I
recall
> reading about it somewhere a while back. Thanks in advance for your help.
>
> Marge
>
>
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