Preparing
stainless steel rods and moulds for kiln work is done slightly
differently from ceramic moulds.
Just to ensure that the steel is of the right grade, I fire it in the kiln to about 720C. This ensures that if the steel is not adequate for the high temperature work, you will find out that it spalls before the glass is put on top. It also has the advantage of removing any dirt and oils on the surface of the metal.
The
separator that you need to put on the steel can be done cold if you
use MR97 or other boron nitride coating. Its main advantage is that
it can be put on cold and also that it has a very smooth surface.
This should be put on thinly, or it will come off onto the glass.
You
can also put standard kiln wash on the metal. The metal needs to be
dry and clean. It could be sandblasted if desired for a bit of extra
“tooth”, but is not normally necessary. Heat the metal to about
120C – 150C in the kiln. Remove it from the kiln with tongs or
similar thing to grasp the hot metal. Spray or paint the kiln wash
solution onto the hot metal. Return it to the kiln as necessary
until you have a coating all over the metal. It does not have to be
even all over, but noes need to have all of the metal covered.
If the
kiln wash boils off the metal, it is too hot. So turn the kiln down
a bit.
If the
kiln wash runs off without sticking at all, the metal is not hot
enough and needs to be returned to the kiln to heat up.
It is
best to avoid applying the kiln wash to the metal in the kiln, as
water and the hot elements do not mix well.
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