Hank Murrow on wed 27 sep 00
one
Vivek wrote
>Hi everyone. I would like to know as to how can we get
>a real rich dark orange or brown colour that would
>look beautiful on salt glazed tiles. I read in a book
>that if you let your Kiln cool slowly you can get a
>rich orange colour and if you cool it down too fast
>the saltglaze will be very dark almost dark coffee or
>purple to black. Is this true.
>I had always thought that if i open up my downdraft
>kiln dome holes early that would give me a light
>colour which i want.
>What i am looking for is a rich saltglaze colour which
>is bright orange and brownish.
>Coould anyone advise me as to how slowly should i cool
>down my kiln after the highest temperature has been
>reached and the salting is complete so that i can get
>my desired saltglaze colour?
>How slow should the rate of cooling be and how many
>hours should it take and at what rate to be completely
>cooled.
Dear Vivek;
I have found that quick cooling in salt produces the colder/bluer tones,
while slow cooling produces the warmer tones. Additionally, a surfeit of
alumina at the surface of the clay will help the orange colors. This could
be a result of choosing the body carefully, or by spraying a light slip of
alumina-rich clay on your tiles. Kaolins rich in iron and titania come to
mind. For the richest color, I would try dampering until the kiln has
cooled to around cone 1; and then firing in oxidation to hold that
temperature for anywhere from 3 to 6 hours. This clear fire condition will
oxidize the iron at the surface and yield the warm colors. Of course, your
firing will have been a reducing fire until the cooling cycle begins. My 28
cuft fiberkiln takes around 18 hours to cool After the soaking cycle ends.
Good Luck, and let us know how it works for you, Hank in Eugene
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