I have just come back from demonstrating “torch enamelling” on
account of being the guest artist (artist-in-residence) at a local
festival here on Vancouver Island. It was a blast.
The reason I do torch enamelling is to provide potential customers
with an understanding as to how enamelled pieces are made. Below is
the way I do it. You will likely read about as many processes as there
are responses to your question.
My demonstration starts with a piece of rectangular copper of 0.5 mm
thick. In general, I fold-form it (isn’t it amazing how many lives
Charles has influenced) because the forms stengthens the piece but
still provides visual interest. The final size is about 3cmm by 4cm.
Strengthening the piece avoids the problem of unequal compression due
to enamelling only on one side. Compression is caused by the enamel
having a higher expansion coefficent than the copper. Compression can
lead to the enamel spalling.
Once the piece is formed I heat it to when the colours of a pigeon’s
throat (gorge de pigeon) appear, let it cool a little, immerse it
pickle (it’s at ambient temperature as I am demonstrating outside
under a tent - there is some splashing but the jar is high and it’s
in a bucket), rinse it and clean it with a brass brush.
Then I apply the enamel (sifting or wet packing whatever strikes my
fancy). Once the piece has the enamel on it, and it is dry, I place
it on top of a mesh mounted on a trivet.
I use brazing fuel or MAP gas, because of the higher heat content
relative to that for propane, and heat from beneath. I always heat
from beneath because otherwise I will blow the enamel away.
This is when the magic occurs. Just before I apply the heat, I let
the audience know what they can expect to see: a layer of copper
oxide forming, followed by the enamels just melting, then forming an
orange peel, and then after some time lightening up as the copper
oxide dissolves in the now molten glass. Lot’s of ooh’s and aaw’s.
I let the piece cool and then pass it around.
It’s that simple. Well almost.
One can make torch fired beads. In that case one heats the copper
tube placed on a mandrel, and while it is hot one spins it around in
the enamel powder and then heats it up again in the flame to melt it;
contrary to what I said above. The difference is that the enamel has
partially melted onto the copper before the heat is applied.
Hope this helps.
David Popham Enamels
"Contemporary designs of an ancient tradition"