John Post on mon 9 jan 12
I have been firing Rovin's RO-82 clay terra cotta for the last 10
years. I bisque to 1922F and use a Majolica glaze over it that I fire
to a large Orton cone 1 or 2. I use commercial lowfire glazes and
underglazes over the top of the Majolica glaze and for whatever
reason, they don't run off the pieces at cone 2.
My students mostly make sculptures, but 5th grade kids do make bowls
for daily use. At cone 1-2 the terra cotta clay is dense and hard. I
started firing this way because kids tend to bonk the work they make
around a bit on the trip home and firing it to cone 1-2 made the terra
cotta so much more durable that there is much less breakage now. The
color of the terra cotta at cone 1-2 is a wonderful deep red and I
like it so much more than the color of the clay when it is only fired
to bisque temperatures.
I have a little aim test kiln hooked up to a computer controller. It
runs off a normal 15 amp household circuit. It's the way to go for a
fast turnaround. I wouldn't even bother with a computer controller
for the little test kiln if you are only using it at temps up around
cone 1-2. I haven't seen any benefit to slow cooling my majolica
glaze so I just let the kiln cool on its own.
If anyone is interested the cone 1-2 majolica glazes recipes I use are
on this page...
http://www.johnpost.us/Pottery%20Links/Glaze%20Recipes/Cone-6-Glaze-Recipes=
.html
John Post
Sterling Heights, Michigan
http://www.johnpost.us
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