Fay & Ralph Loewenthal on fri 21 jun 02
Dear Barbara, I have just restarted glass fusing and slumping
in my two kilns. I have a 6.5 cubic foot front loader and 1.6
cubic foot Paragon top loader, recently purchased at a really
bargain price. The controller alone is worth more than I paid=20
for the kiln etc. Any way I digress. I have fused in the large=20
kiln, at first disastrously, now having success most of the=20
time. I tried slumping in the small kiln and the two pieces
cracked up. Here is the process I use. Please note all my=20
measurements and temperatures are metric.
I use float glass, the stuff they use for window panes, so my =
temperatures are for that type of glass. I would suggest you=20
get temperatures from your glass supplier. Bullseye and other
"art" glasses tend to fuse, and slump at lower temperatures.
I use a "programmable" controller, which is a must if you
want to sleep comfortably.
I start by cutting my piece out of 3mm glass X 2. I put=20
whatever colouring I want in between the two pieces of=20
glass. I then fuse the glass first. I go up 50 degrees C per=20
hour until 300 degress C. I then fire up to 830 degrees C at
100 degrees C per hour. I then open up the kiln and drop
the temperature to 500 degrees C. The kiln then soaks for=20
2 hours at that temperature. My front loader usually takes
about 12 hours to cool to about 40 degrees C, which is when=20
I open up. I fuse first to get nice rounded edges, which I=20
prefer to sharp, square edges. Rounded edges give a better
quality look to the piece. I then slump using the same=20
ramping, but only up to about 750 degrees C, depending on
what I am slumping, over what or through what. The nice=20
thing about glass is that you can open the kiln once the
temperature is over 500 degrees C. So I start having a look=20
from about 650 degrees C. One slump over stainless steel
and into ceramic moulds. The reason is that stainless steel
expands and contracts more than glass, whereas ceramics
COE is less than glass. I have bought some very nice stainless
steel platters, bowls etc from cheap shops. Of course I make=20
clay moulds myself.
As far as I know Boyce Lundstrom has written at least two
books. If you are serious about hot glass work these are a
must. Unfortunately they are not available here in South=20
Africa. I borrowed a friend's copies.=20
Hope this helps, kind regards from Ralph Loewenthal in Cape
Town South Africa.
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