MIG welding questions

Welding yesterday with my little Lincoln SP125+ I noticed something I had not seen before. I was welding aluminum with .035 4043 wire with
the welding machine close to max voltage and wire speed. My new auto darkening hood makes it MUCH easier to see what is going on in the arc and I could see the wire in the middle of the arc vaporizing and the weld bead being deposited. It was kinda like magic. There was this zone where there was no visible metal. So I guess the welder was doing spray transfer. Then I noticed that it made a huge difference in weld appearance whether I pushed or pulled the gun. Pulling the gun left the weld black while pushing it left the weld clean. My questions are is the black deposit aluminum oxide and is spray transfer the proper way to MIG weld aluminum? Thanks, Eric
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On Monday, April 13, 2015 at 12:42:45 PM UTC-4, snipped-for-privacy@whidbey.com wrote: My questions are

You ought to post this is Sci.engr.fastening.welding and see what Ernie say s.
My understanding is that Spray is the way to go when welding aluminum. I t hink you can weld aluminum using a Constant Current source in spray mode. In other words you can use your SP125 just to feed the wire and use an AC s tick welder as the power supply.
Dan
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