
The glass is blackened due to an orange flame being used to initially warm the glass before the blue flame does it's thing. As you may see from the wire used to slice the tubes, a very hot very quick action on the glass will destroy it.
My favourite part was the home made spot welding rig.
Edit:btw enjoyed the video and was typing when 'My Front Fell Off' posted. It's a good sign that we both agree. d;]
( , Mon 23 Jul 2012, 23:54, Reply)

That rough casting, that fly press action, those shiny electrodes... and she twitches when you flick her switch.
( , Tue 24 Jul 2012, 1:03, Reply)