Learned something new about MIG welding:
* Welding with shielding gas is not practical for windy conditions.
* Flux cleans the metal and keeps it from oxidizing while you're welding.
* Welding with shielding gas keeps your weld from spattering molten metal all over and gives you a cleaner weld.
* Welding with solid core and shielding gas is best for inside work on clean metal.
* Welding with flux core and no shielding gas is good for outside work on unclean metal.
* Welding with flux core and shielding gas is good for inside work on unclean metal.
I'm still not clear on the polarity stuff and the proper gas mixtures for each type of MIG welding.