How does this work, would the paint get slightly burned?They were originally done with a brazing torch set to run dirty....candling.
Arthur Barnstonworth used to do it with a lit woodbine and a handful of saltpeter.Im not entirely sure if that was how it was done at diamond back, but its certainly how the old timers did that effect.
I assume you just run too much acetylene with little to no oxy. If you shut down a torch you can fill the workshop with floating black strings of soot if you try hard enough......