Wayne Pelke on fri 6 aug 04
Hi Everyone:
I have been sculpting in clay for about 20 years and because I use “cold” finishes (mostly washes in acrylic paints) to patina my pieces, I am a neophyte when it comes to “hot” finishes. I am not really interested in using glazes; however, I would like to experiment with washes containing only oxides and water. I primarily use a white, raku stoneware clay. My question is: at what temperature (or cone) does an oxide need to be fired in order to permanently adhere to the bisqued clay? Or, for that matter, can a simple wash of an oxide be made to adhere to bisqued clay? I would appreciate any help. Wayne Pelke
P.S. If anyone is interested, he/she can see some of my work at www.sculpturebypelke.com.
Carolyn Bronowski on fri 6 aug 04
Hi Clayarters and Wayne. Thank you for sharing your web-site, beautiful
work. I use mason stains mixed in a base stain fired to ^06 on bisqued IMCO
sclupture mix, 412. I don't like mason stains mixed in water. The stain
colors mixed in a stain base hold ture and with a sponge, I can really vary
the depth of color. In fact, after I took the piece out of the kiln, I
noticed that I forgot to put some color on one part, I simply sponged on
some walnut mason stain, and I don't even have to refire ithe piece--the
stain does not come off on my fingers. Of course, this piece will stay
inside the house. I bisaue to ^08. Cheers from Modesto, a comfortable 95
degrees. Carolyn
Darlene Fletcher on sun 8 aug 04
Hi. During my sculpture courses at university some 20 years ago (!), we
mixed various types of oxide washes for stoneware sculture fired to ^6-^9.
The most common was a mix of manganese dioxide with a slight pinch of
cobalt. By applying it once or twice and wiping back, a lovely antique look
was created when used over buff coloured clay. It adhered at lower temps as
well, but at high temps took on a nice sheen. Today, however, I stray away
from manganese because of it's potential toxicity. I often have kids
working in my studio and have become somewhat paranoid. As an alternative
to oxides, I now use tan/brown/black underglazes (I prefer Duncan) and fire
to ^4-^6. After I apply them, to get a nice sheen, I apply a VERY thin coat
of ^6 clear glaze. This works great.
Darlene
Snail Scott on sun 8 aug 04
At 12:49 PM 8/6/2004 +0000, you wrote:
>I am not really interested in using glazes; however, I would like to
experiment with washes containing only oxides and water. I primarily use a
white, raku stoneware clay. My question is: at what temperature (or cone)
does an oxide need to be fired in order to permanently adhere to the
bisqued clay?
The temperature that an oxide will fuse at
varies with the oxide. Generally, though,
using an oxide by itself will not result in a
well-bonded surface unless the coating is quite
thin. I would suggest adding a little frit or
a little clear glaze to the oxide to help it
bond. I would also add a little clay to it.
Many oxides are very strong colorants, and you
will be able to control the strength of the
color better if the oxide wash is 'padded out'
with clay. The clay will also allow the wash
to stay suspended better in water. (A little
CMC gum will help with manageability, too.)
Stains (real ceramic stains, not those acrylic
paints called 'stains') can also be used the
same way, to extend your color palette. Stains
come in dozens of colors that raw oxides just
can't achieve.
If you do this (mixing oxides or stains with
a little clay) you are already halfway to
making engobes. As you may know, you can't just
apply wet clay to bisqued clay unless it is
very thin, like a wash. But if you also add
calcined clay to your mix, you can apply it in
thicker coatings for more painterly effects
which, unlike paint, will be both durable and
archival. You can make you own calcined clay
by putting a bowl of dry clay powder in a
bowl and bisquing it, or you can buy it. Try
different amounts of clay and calcined clay
and colorants to see what combination you like
best. A 50/50 blend of clay and calcined clay
is a good starting point. Then add colorants
to suit you. If you use stains, you can mix
the resulting batches like paint, brushing
and blending, and the colors you see will be
the colors you get. They will be pastel-like
if left uncovered, or you can coat them with
clear glaze to deepen the color. You can also
add a little clear glaze to the engobe itself,
to change the glossiness. Engobes will work
over a wide range of cones; they are much
less fussy than glazes. They can also be
layered on each other. The exact proportions
don't matter. Just play with them until you
like what you get!
-Snail Scott
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