Part One
Ok. I have been doing a fair job of welding 5000 series aluminum with 5000 series wire, but it spatters a lot, and is sooty. I read the submarine guy's website about how he decided to use 4000 series wire to weld his submarine, and was much happier with the results... Mostly he was not happy witth the spatter and soot using 5000 wire.
So what is his submarine going to do as far as corrosion resistance at the seams? How about strength? The reason I ask is that almost all of my own alumiinum welding has been for boat (fresh water) repair. If I could do a better job with 4043 welding wire I would switch in a second.
Part Two
I have been told its, and pretty much gone along with using straight argon for welding aluminum. I have also brushed the heck out of everything I have welded with stainless brushes. I have a drawer in one of my rollaways now just for stainless brushes for aluminum. I seem to recall it being mentioned that argon/ Helium mix in some percentages will weld aluminum better in some circumstances and even weld dirty aluminum. What does that mean, and were would I lear more about that. I just so happens I have an extra oxygen bottle I could swap for another mix bottle. (after I use up the oxygen in it)