Pressing gas cylinder concave bottoms - GIF

[Toolmaker51]

1st operation, looks as though dumping out slag; carbon layer formed getting the end up to forming heat.
Sure, it's upended again just seconds later, but it's disposed 'overboard', versus into the machine.
It's only a second long, but at 0.05' the glowing pile is right at open mouth of cylinder.
Just noticed; still shot in the mail shows it almost perfectly, video has it spilling out.