Do you all understand that when you use a torch on metal...it's gonna leave a black smoke residue (soot) on the metal? So if you got a little slag build up around the edges you're cutting...and then it has this black smoke residue on top of it...you think that means the slag is black?
Do you see any black smoke residue on this steel column:
http://img243.imageshack.us/img243/2271/thermiteut7.jpg
NO, all you see is a big black gook of IRON that has melted on top of it. Couldn't be any more obvious...
Nobody here would bet their house that the black molten metal in this pic is actually slag from where a torch cut it...I'm just speechless that you people are claiming that.