Slumping glass can be fun, but it is not easy to do with any
precision. You mentioned "tiny domes". Glass will not slump into
tiny shapes just from its own weight unless you slump a way
oversized piece and cut it down. Even then, it is likely to fold
more than mold. In addition, it will take on the texture of whatever
you mold it onto, so it won't just be shaped clear glass. The change
in texture can perhaps be avoided if you only slump it slightly, but
domes will require considerable movement/heat/softening.
If you do try this, be sure to ramp the temp down very slowly, maybe
with a "soak" at annealing temp-- I think that's about 850, but it's
been a long time... Otherwise, the piece may self-destruct from
I used to make forms out of bisqued clay, and paint them with
whiting or kiln wash to keep the glass from sticking. These were
Thinking about it now, I think if I wanted a dome, I'd start with a
sheet of glass at least three times the width of the dome. I'd cut 2
sheets of metal-- heavy copper would probably work-- oxidation will
prevent the glass sticking to it-- the same size, and cut a hole the
size of the dome in the middle of both sheets. I'd sandwich the
glass in the copper and put it in the kiln up on bricks so there was
space under the hole, and weight the top as well so the glass would
stretch, not slip. Then heat and watch until the glass stretched
down into shape, cool the kiln slightly to stop it, close it down to
cool as slow as possible. Later, cut off the "flange".
All in all, there must be an easier way.