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red stains & underglazes, glazes used over them

updated tue 26 jan 99


Thonas C. Curran on thu 21 jan 99

David Hewitt wrote:
> ----------------------------Original message----------------------------
> I use a cadmium containing stain called B185 Coral. I add 6% to a clear
> transparent glaze and apply thickly. Thickness is important for
> achieving a dark red colour. You can see examples of the result on my
> web site under 'Pink Lustre' if you are interested.
> This is fired to cone 8 oxidation over a white stoneware clay, but I see
> no reason why it should not work in a cone 6 glaze if required.
> David
David and other Clayarters:
What about the glaze used with all these cadmium and other red stains,
underglazes, etc? I have not done extensive testing at all, but I have
tried various red underglazes and stains, then have dipped the test
tiles in a variety of clear glazes. Firing to cone 5 or 6, I've come up
with varying success (in obtaining a clear red) depending on the glaze
used on top. Has anyone done this in a more thorough manner? I never
did follow up to see which glaze ingredients were influencing the result
on the stains, etc. So many interesting things to investigate, so
little time.........carolyn aka cnc

Beth J. Leggiere on sun 24 jan 99

You don't say what the other types of red stains are. Many non-cadmium
reds are obtained with chrome and tin working together. If you are
using a chrome-tin stain, such as Mason deep crimson, you must have at
least 12% elemental calcium in your overglaze, or the color will fade
away at cone 6. If you are using commercial underglazes, the
manufacturer should be able to recommend an appropriate overglaze for
the colorants in their product. I use both cadmium and chrome-tin
stains in glazes and find reading the stain description and all the
footnotes in the supply catalog important for good results and to avoid
wasted time. Most of the supply store catalogs have charts that list
stains and their reqirements to work well. If you don't know if the
stain is chrome-tin or cadmium, price is a good way to guess (cadmium is
very expensive) or do a test, using your regular over glaze on one side
and a high calcium glaze on the other. If both sides come out, it's
likly cadmium, if only the high calcium side comes out, it's probably
chrome-tin. Stains are great, I love working with them, but they can be
frustrating. good luck!

Beth Leggiere

Thonas C. Curran on mon 25 jan 99

Dear Beth, Thank you for your reply about the red stains, etc.
Actually, I usually go to all written sources on hand before asking
someone else about a certain subject (and I have a bookcase full of
source material) but I really do not recall much definitive information
in the catalogs other than temperature limits and such. I will look
more carefully and see what I can find once I get offline. I do
appreciate your leads, though!
Just how high a temp have you been able to push some of your red
stains? I would be interested to know of someone else's experience. I
wonder if there is such a mystique about reduction copper reds (and even
iron reds) that there is not much written in books about Mason stains,
etc. There is nothing in my estimation which comes close to a great
copper red, but copper reds aren't the only story. I wonder if those
who write the books are so used to working with reduction kilns that
writing about other ways of gettings reds is not on their priority list.
(Discussion, anyone? I may be off base because of ignorance, but I'm
talking mainly about books, not CM articles and such. ) Thanks again.