Jinx,

I do some glass blowing myself. Pressed (molded) glass is never ok without
polishing even for the simplest optical tasks. If your item is decorative
then you may get away with it. A clock face is not (did I guess ? ;-).

The smoothest surfaces are obtained by pouring molten glass onto a liquid
metal bath. This is the way most window glass is made. You could in theory
have the molten metal bath spin to create a meniscus and pour into that
but I suspect that you do not have a free room in your glass factory to
accomodate the equipment ;-).

Don't even think about steel molds. Precise lass molds are made of
graphite or other refractory and low thermal conductivity material
usually. Steel molds are used to make beer bottles and the like and they
have special linings and are pre-heated and otherwise specially handled.

For a moderate diameter item (up to about 30 cm - 1ft diameter and <3kg) a
local *skilled* glassblower can help you out. A skilled glassblower can
blow a flask composed of two 'watch glasses' in a go, one with a blowhole,
and one without. You or him can later separate them at the rim, using his
methods or a grinding stone. We once had lamp shades made like this
(without separating the halves).

Make a nice drawing and find a local glassblower artisan shop imho.

hope this helps,

Peter

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