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I should also point out that when welding aluminum, cleaning the filler rod is way more important than it is when doing steel. The aluminum has loads of draw lube on it from when they made the wire. That's the black gunk you see when you wipe them down. I don't care what you clean it with, even a dry cloth is better than nothing. But there's a BUNCH of gunk on filler metal. And it's not really a bad thing, it helps to control oxidation to some degree. It just needs cleaned off before you weld with it.

weld.com utube channel has some absolutely superb footage of gunk on the filler wire going into the pool.