Jay S. Gertz on tue 17 nov 98
Hi all!
Here's something I don't see addressed in any of the pottery texts that
I commonly use: formulas for oxides used as colorants. I frequently use
red iron oxide, or rutile, or chrominium, or copper carbonate as
colorants under glazes. Unfortunately, their hue and tones tend to be
variable. Does anyone know of a specific water to oxide formula to
guarantee a good result most everytime? Also should I be using a little
glycerine to make application easier. I usually brush it on. And this
is for cone 5-6 oxidation firings. Thanks, Jay
June Perry on wed 18 nov 98
Dear Jay:
I don't know about specific proportions, but I go for a watercolor
consistency. I make the solution as thick as I can and still see the paper
underneath on a single brushstroke. With oxides like chrome, I go a little
lighter because of it's refractory nature. A little goes a long way.
Do a bunch of test batches starting say, with about 2-3 teaspoons of oxide
mixture per cup of water. Do the brush test on a piece of paper. If it looks
too weak, add more oxide about 1/2tsp at a time. If it looks too thick, add a
bit more water and keep good notes! This will give you a place to start. Some
oxides like managanese are weaker and would need a stronger concentration to
give the color you want.
The best advice I can give is to make a bunch of tests since not all the
oxides require the same amount of water. Make a whole bunch of flat test
tiles about 3X5 inches for instance, and use those to test your oxides over
and under the glazes you are currently using.
Warm regards,
June
David Hewitt on thu 19 nov 98
Hello Jay,
I think I can understand your problem. I think you would be able to get
more consistant results if you mixed the oxides into a slip and then
applied by brush. I use this method a lot and details of how I make the
slip is given in my web site under Pottery Techniques.
http://www.dhpot.demon.co.uk
Might be worth a read
David
In message , Jay S. Gertz writes
>----------------------------Original message----------------------------
>Hi all!
>
>Here's something I don't see addressed in any of the pottery texts that
>I commonly use: formulas for oxides used as colorants. I frequently use
>red iron oxide, or rutile, or chrominium, or copper carbonate as
>colorants under glazes. Unfortunately, their hue and tones tend to be
>variable. Does anyone know of a specific water to oxide formula to
>guarantee a good result most everytime? Also should I be using a little
>glycerine to make application easier. I usually brush it on. And this
>is for cone 5-6 oxidation firings. Thanks, Jay
>
--
David Hewitt
David Hewitt Pottery ,
7 Fairfield Road, Caerleon, Newport,
South Wales, NP6 1DQ, UK. Tel:- +44 (0) 1633 420647
FAX:- +44 (0) 870 1617274
Own Web site http://www.dhpot.demon.co.uk
IMC Web site http://digitalfire.com/education/people/hewitt.htm
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