[T77911S]

polarity is reversed if using flux core vs wire with gas.

not an expert at welding by any means but even rusty or dirty metal wont cause it to pop, I have tested welding rusty crap like rebar.

someone said it earlier. too much heat with too slow a wire feed.

here is what I have done when I first started.
while welding, take your other hand and adjust the wire feed up and down. listen to how it sounds when the wire feed is too fast and too slow.
listen for when it sounds like bacon cooking.

change the heat setting and then repeat and notice how the weld changes.

I practiced a lot with flux core just because it was cheaper.
if the polarity is reversed you will get a lot of little balls that will stick to the metal that are a pain to remove.
it seemed like the flux core welded cheap soft metal better.

I also spent a lot of time trying to weld thin metal. I figured that was harder than thicker.

my welder will also do stick welding. my stick welding is worse than my mig so I work on that more.

I cant believe I went as long as I did with out a welder.
Saturday I welded an allen wrench to the small screw that holds a brake rotor on.
then welded a bar to large nut that holds the shock inside a front strut.