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bluestone and sawdust firing

updated fri 24 oct 97


Sylvia See on mon 13 oct 97

I use bluestone all the time for my sawdust fired pots. I bisque to cone
06, then use a foam brush and apply three thin coats of bluestone mixed
with water. I use about 3 large tablespoons to 1/2 cup of water. I apply
each coat coat a different direction from the last one. Watch for drips and
runs and try to apply it evenly. If you get it too heavy it becomes crusty
or eats into the surface of the piece and ruins the burnished finish. I
burnish most of my pieces and the bluestone in sawdust firing, gives colors
ranging from yellow, orange, lime green and reds, from the sawdust. I have
had all of those colors in the same firing with pieces all made from the
same clay. Must be something in the sawdust that reacts to give the
different effects on pots in the same firing. Man I love to finally open
the kiln. I fire in old electric kilns for several days. Great stuff. I
love it. Really interesting with burnished red clay.
I get my bluestone from farm suppliers, and also use it to keep the algae
down in the pond in my yard. They use it to treat fence posts to keep them
from rotting in the ground I have been told. I wear thin medical rubber
gloves when working with it. It is called copper sulfate I have been told.
I also sprinkle vermiculate and either blue or red farm salt that I get
from the UFA around the pieces between layers of sawdust. This gives an
unusual pattern and it slowly burns down at different rates around the
pots. The vermiculate leaves small circle effects on the pieces, acting
like a shield similar to putting clay pieces on pot for pattern effects. If
you wrap the pieces with white tissue you will get a blacker finish, with
not as much color flashing, I have found. However, placing leaves and
flowers etc and then wrapping with about 3 layers of white tissue, give
great fossil effects on the pieces. Note: if wrapping with tissue and
tacking the tissue with masking tape, make sure the tape doesn't touch the
pot or you will get the tape impression on the pot. Also, writing a design
on pot with felt marker will act like a resist, leaving a pattern.
Darn, I haven't sawdust fired for a couple of years. This is making me
want to get back into it. We find it hard to market here for the amount of
work you put into burnishing and waxing. I always priced my primitive
higher than my glazed pieces, and the public are slow to appreciate why.
Sylvia See Claresholm, Alberta
I really like my bifocals
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