As others have said, you will need an annealing oven. We used natural
gas-oxygen in the glassblowing class I took many moons ago. Acetylene air
might be ok, but acetylene oxygen is way to hot. You need a small torch
with a fine tip, as I recall the inner blue cone was about 1/8" diameter at
the base and about 1/4" long when working borosilicate glass in the 6-15 mm
OD range. A glass lathe is really nice to have when doing ring seals on
condensers. Of course we had to learn to do it freehand before we got to
use the lathe since it made it so much easier :-). You can learn by
yourself from books but this is one case where access to a real glass shop
would be invaluable. See if any local junior colleges or other schools have
a class you can take. Even if they don't, go meet the instructor and bribe
him into doing some demos and letting you use his torch and oven :-).

-----
Regards,
Carl Ijames
"RogerN" wrote in message
...


Messing around with chemistry and such, would sometimes be nice to be able
to fabricate with the glass tubes. I can bend them easy enough with just
the alcohol lamp, propane torch does even better.

I can make a poor man's condenser using a small diameter tubing for the
vapor and a larger tube for the water cooling jacket, rubber stoppers at
each end of the larger jacket tube, 2 holes in each stopper, one hole for
the vapor tube that passes through and another tube on each end for cooling
water inlet and outlet.

This could be done neater if I could weld glass nipples onto the cooling
jacket, and neck down each end of the cooling jacket and weld to the tube
that runs inside. I've been playing with the glass with a propane plumbing
torch, seems difficult to work. When trying to weld, too large of an area
of glass gets too soft, I think I need a flame that is more concentrated,
heating to melting temp right at the joint but not so much to the
surrounding glass.

Anyone here tried working with borosilicate glass with metalworking welding
torches? I don't see why it wouldn't do what I want (joining glass) but I
don't have the tanks anymore. I don't mind getting the tanks, but I would
like for it to work before I lease tanks and buy oxygen & acetylene (or
propane). When I had tanks, I had them for several years and hadn't used
half of my gasses up yet, that's why I took them back, I was paying monthly
rental on something I hardly ever used.

RogerN