Glass rods get grumpy when you use oxy-acetylene on them.
A propane torch works better as it burns cooler and won't cause your glass rods to shatter from heating too fast.

Similarly, when melting glass rods you don't really want to use a scrap of leftover ceramic tile as a work surface if you're being dumb enough to use oxy-acetylene, as it will pop apart violently and sent extremely hot bits in directions you don't want.

Glass is very snarky stuff.
( The Resident Loon Not a demographic. Do not measure., Thu 14 Feb 2008, 20:00, 3 replies, latest was 17 years ago)

Geek alert!!
Your scarying me now : )
( girlinthehole, Thu 14 Feb 2008, 20:04, Reply)

Found this out by trial and error.
There are little bits of dark green glass all over my patio now, and the ceramic tile I was using is in a lot of bits. But after playing around with it, I did manage to melt some glass into basically a mushroom shape at the end of a rod.

This is how one learns about such things. Besides, it involved playing with fire.
( The Resident Loon Not a demographic. Do not measure., Fri 15 Feb 2008, 13:22, Reply)

I do this sort of thing frequently!
We have a bench in the lab with glass rods, tubes etc, and a nice big gas torch.

Quartz rod is the most fun - it doesn't melt until it's white hot. Dropping a molten blob into a bucket of cold water is quite entertaining.
( K2k6 has a proper job these days, Mon 18 Feb 2008, 15:47, Reply)