Could be a remote possibility, but I was going by the original post stating it was clean.
It cools and POP it breaks loose! The metal is clean, I ground it off until it was shiny!
Dave
Second to that, it's been my experience that most people green to welding automotive sheet metal have it drilled into their head that they need to use low heat to keep distortion to a minimum, with no consideration mentioned of weld penetration, and most of what you see in pictures are cold welds sitting on top of the panel. I'd say
ALL of the welding critiques (re: when pictures were posted) that I have given to those asking for such feedback has been such that the welds were cold and they needed to distance themselves from previous advice and turn up the heat. IMO weld penetration is the priority, first and foremost.
Back to your suggestion, even given enough contamination that would create a porous weld in sheet metal, the weld joint does not typically just "pop" off from the base metal if ADEQUATE heat is present. Now a new guy welding sheet metal too cold, that happens all the time. I stand by my statement, not enough heat, even without looking at pictures.
