Ken Russell on sat 17 jan 98
Ron, I need some help with my green. I use straight metal oxides mixed with
water for color. I use Spanish red iron oxide for brown, cobalt ox for blue
and black copper ox for green. I brush on the oxide when the pot is leather
hard. I carve through the brushed portion with various decorations, bisque
then glaze with an opaque base glaze and fire to c6 ox.
I've figured out how to be consistent with the red iron and cobalt but the
green is REAL touchy. A slight overfire and it goes dark olive. If the
base glaze isn't applied thick enough, it results in a throw up looking
yellow-green. One customer who actually likes it has titled that color:
Barphe. I've been playing with and testing chrome and cobalt carb to get to
a hunter green but so far, no cigars. When the black copper works, it is a
beautiful hunter/turquoise color. The brush marks add nice variations too.
What I'm wondering is if you know of a better combination of oxides
resulting in green that I could be testing. My opacifiers in the base glaze
are zircopax and tin oxide. Too much tin and I get too much rust, screwing
up the copper green. Too much zirc gives me an overexposed sort of lame
white. I think I have the combinations of zirc and tin right for the base
glaze but maybe you have suggestions for that with respect to how it affects
the copper. Any recommendations would be appreciated.
Ken Russell
The Arlington Pottery
gone2pot@iw.net
David Hewitt on tue 20 jan 98
Hello Ken,
I think that I am familiar with your problem. I decorate much of my work
in a similar manner to what you describe. However, I do not now use
straight metal oxides mixed with water as I found it difficult to
maintain the same 'strength' in the final result as you describe. I now
make up a slip by mixing the metal oxide into the same clay as the body.
For copper oxide, for example, I mix 5% by weight into clay body (dried
turnings ground and sieved and weighed) and then add water to make a
slip which will easily brush on leather hard pieces. Copper oxide is
still prone to variation, according to the thickness with which it is
brushed on, but I find it more controllable in the form of a slip.
Other oxide proportions that I use are:-
Cobalt oxide 1.5%
Iron oxide 15%
I also use stains in the same way.
David
In message , Ken Russell writes
>----------------------------Original message----------------------------
>Ron, I need some help with my green. I use straight metal oxides mixed with
>water for color. I use Spanish red iron oxide for brown, cobalt ox for blue
>and black copper ox for green. I brush on the oxide when the pot is leather
>hard. I carve through the brushed portion with various decorations, bisque
>then glaze with an opaque base glaze and fire to c6 ox.
>
>I've figured out how to be consistent with the red iron and cobalt but the
>green is REAL touchy. A slight overfire and it goes dark olive. If the
>base glaze isn't applied thick enough, it results in a throw up looking
>yellow-green. One customer who actually likes it has titled that color:
>Barphe. I've been playing with and testing chrome and cobalt carb to get to
>a hunter green but so far, no cigars. When the black copper works, it is a
>beautiful hunter/turquoise color. The brush marks add nice variations too.
>
>What I'm wondering is if you know of a better combination of oxides
>resulting in green that I could be testing. My opacifiers in the base glaze
>are zircopax and tin oxide. Too much tin and I get too much rust, screwing
>up the copper green. Too much zirc gives me an overexposed sort of lame
>white. I think I have the combinations of zirc and tin right for the base
>glaze but maybe you have suggestions for that with respect to how it affects
>the copper. Any recommendations would be appreciated.
>
>Ken Russell
>The Arlington Pottery
>gone2pot@iw.net
>
--
David Hewitt
David Hewitt Pottery ,
7 Fairfield Road, Caerleon, Newport,
South Wales, NP6 1DQ, UK. Tel:- +44 (0) 1633 420647
URL http://digitalfire.com/education/people/hewitt.htm
Ron Roy on tue 20 jan 98
Sorry Ken - don't do much at 6 so just don't have answers for you - All my
glazes are with iron at cone 10. There must be at least a hundred
ClayArters who could help with this!
>----------------------------Original message----------------------------
>Ron, I need some help with my green. I use straight metal oxides mixed with
>water for color. I use Spanish red iron oxide for brown, cobalt ox for blue
>and black copper ox for green. I brush on the oxide when the pot is leather
>hard. I carve through the brushed portion with various decorations, bisque
>then glaze with an opaque base glaze and fire to c6 ox.
>
>I've figured out how to be consistent with the red iron and cobalt but the
>green is REAL touchy. A slight overfire and it goes dark olive. If the
>base glaze isn't applied thick enough, it results in a throw up looking
>yellow-green. One customer who actually likes it has titled that color:
>Barphe. I've been playing with and testing chrome and cobalt carb to get to
>a hunter green but so far, no cigars. When the black copper works, it is a
>beautiful hunter/turquoise color. The brush marks add nice variations too.
>
>What I'm wondering is if you know of a better combination of oxides
>resulting in green that I could be testing. My opacifiers in the base glaze
>are zircopax and tin oxide. Too much tin and I get too much rust, screwing
>up the copper green. Too much zirc gives me an overexposed sort of lame
>white. I think I have the combinations of zirc and tin right for the base
>glaze but maybe you have suggestions for that with respect to how it affects
>the copper. Any recommendations would be appreciated.
>
>Ken Russell
>The Arlington Pottery
>gone2pot@iw.net
Ron Roy
93 Pegasus Trail
Scarborough,Canada
M1G 3N8
Evenings, call 416 439 2621
Fax, 416 438 7849
Studio: 416-752-7862.
Email ronroy@astral.magic.ca
Home page http://digitalfire.com/education/people/ronroy.htm
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