McCoy, Jack Eugene on thu 9 oct 97
I'd like to find or formulate a cone 9 glaze that produces a
gloss/semi-gloss strong green. I've checked various books and the
online database but keep coming up with a lot of blue-greens and light
greens. And when I check the reference books they point to copper oxide
as a source of green. But then they go on to say that if copper oxide
is fired in reduction it'll produce red.
Also, chrome is mentioned as a source for green glazes. But according
to the same books they say that it vaporizes (or a simliar word) at
lower cones.
What colorant(s) can I use in a cone 9 reduction kiln to get something
like an emerald green?
Thanks in advance for your help,
Jack
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Jack McCoy
Systems Programmer
East Carolina University
Voice: (919) 328-6855
Fax: (919) 328-4258
email: mccoyj@mail.ecu.edu
douglas gray on fri 10 oct 97
Jack,
You'll probably get better advice from others, but...
Chrome will give you a strong green at c9 in reduction. You actually don't need
to use much (1-2%) Chrome is a kind of frog green, can be army helmet green in
some recipes. Also tends to be a very flat even color--good if you are used to
low fire underglazes, bad if you are use to the depth and texture of high fire
glazes. In chrome glazes, small additions of titanium can break up the surface
some, creating texture, but it does change the color response as well.
Copper will give brighter greens, can do so even in reduction. The base recipe
will determine whether or not it goes green or red. Avoid any glaze that has
tin oxide in it. Tin is used to help copper turn red. Another thing to
consider is the other glazes you will be firing in the same load. Copper can
flash the other glazes, making red or pink flashes where you didn't expect to
see them. Can be quite beautiful though. Some of these copper green glazes
tend to flash red or pink even by themselves, experiment.
Iron will give greens also in small amount (1-3%) These are the more
traditional green you see on Chinese celedon pieces. If you over do the amount
of iron it may go brown to black, if used in large amounts. That's where the
temmoku glazes come into play. Celedon greens are typically pale in comparison
to other hues, but create deep lush surfaces that can highlight surface/relief
decoration
Of course, any of these colorant can be used in combination. For example, small
additions of iron can tone down a copper green glaze if it is too bright.
Additions of chrome can help to produce more of a grass green when used in
conjunction with copper. Small amounts of Cobalt can be added to any of the
above to give the green a blueish tone.
You might want to check out the available stains. Stains can be used to create
a variety of different shades of green. Green is one of those colors that seems
to withstand the high fire temps as does blue and green/blue combinations.
Check with the dealer to be sure.
Above all remember....It ain't easy being green.
good luck,
doug
=========================================================================== =)
Douglas E. Gray
Assistant Professor of Art, Ceramics
Francis Marion Univeristy
Florence, South Carolina 29501
dgray@fmarion.edu
Paul Lewing on fri 10 oct 97
Jack,
Green is pretty easy to get at cone 9, or even higher, with chrome.
It does not volatilize at that temperature, and is pretty unaffected
by reduction. You will get varying shades of green depending on your
baase glaze, as long as there is no zinc present. Zinc will make
chrome go brown. Chrome does produce some pretty harsh greens,
though, so you may want to modify it with small additions of cobalt,
rutile, titanium, manganese, iron, or nickel. You might even try some
of the high-chrome Mason stains as a source for your chrome, although
in reduction they tend to all come out looking like straight chrome
oxide. Also a small addition of flourspar to the base glaze can
result in interesting changes to the shade of green.
Happy testing,
Paul Lewing, Seattle
Karl P. Platt on fri 10 oct 97
Chrome in a Ca rich host will give your best results.
Peggy Heer on sat 11 oct 97
Hi Jack...use Yellow Ochre for your colorant for a strong dark green in
reduction.
I have a great rec. if you need one.
As Always in Clay Peggy
>----------------------------Original message----------------------------
>I'd like to find or formulate a cone 9 glaze that produces a
>gloss/semi-gloss strong green. I've checked various books and the
>online database but keep coming up with a lot of blue-greens and light
>greens. And when I check the reference books they point to copper oxide
>as a source of green. But then they go on to say that if copper oxide
>is fired in reduction it'll produce red.
>
>Also, chrome is mentioned as a source for green glazes. But according
>to the same books they say that it vaporizes (or a simliar word) at
>lower cones.
>
>What colorant(s) can I use in a cone 9 reduction kiln to get something
>like an emerald green?
>
>Thanks in advance for your help,
>Jack
>
>
>
>=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
>=-=-=-=-=
>Jack McCoy
>Systems Programmer
>East Carolina University
>Voice: (919) 328-6855
>Fax: (919) 328-4258
>email: mccoyj@mail.ecu.edu
Peggy Heer / Heer Pottery E-Mail p4337@connect.ab.ca
52120 Range Road 223
Sherwood Park, AB. Canada T8C 1A7
Phone (403) 922-6270
http://www.ffa.ucalgary.ca/artists/pheer/
David Jay on tue 14 oct 97
McCoy, Jack Eugene wrote:
>
> ----------------------------Original message----------------------------
> I'd like to find or formulate a cone 9 glaze that produces a
> gloss/semi-gloss strong green. I've checked various books and the
> online database but keep coming up with a lot of blue-greens and light
> greens. And when I check the reference books they point to copper oxide
> as a source of green. But then they go on to say that if copper oxide
> is fired in reduction it'll produce red.
>
> Also, chrome is mentioned as a source for green glazes. But according
> to the same books they say that it vaporizes (or a simliar word) at
> lower cones.
>
> What colorant(s) can I use in a cone 9 reduction kiln to get something
> like an emerald green?
>
> Thanks in advance for your help,
> Jack
>
> =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
> =-=-=-=-=
> Jack McCoy
> Systems Programmer
> East Carolina University
> Voice: (919) 328-6855
> Fax: (919) 328-4258
> email: mccoyj@mail.ecu.edu
Jack
Here is a glaze one of my students made up several years ago that
"Might" satisfy your request. This is a very opaque, thick(don't apply
any thicker than normal)rich green. Cone 9 reduction
RANDY'S DREAMY TORQUOISE
Potash feldspar 46%
Whiting 18
EPK 7
Flint (200) 29
+ Combines ok with dry matt whites.
chromiun ox 1 Does not take oxides well.
cobalt carb 0.50 *This will run if applied too thick.
Happy Glazing I hope this works out for you.
Paul
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