Aluminum Contamination

[zx1200r]

Either electrode, pure or 2%, works well. The 2% just seems to focus the arc giving more control.
When I first start the weld it leaves a black spot.

[zx1200r]

I have a stainless brush that i use for aluminum only. I also used a propane torch to heat the aluminum and burn away the moister.

[zx1200r]

Please look at the pictures in the link below. I'm welding 1/4" aluminum with 1/8" 2% Thoriated on AC. The welds seem to get contaminated with the 2% but look cleaner with the pure. Is the tourch suppose to look like photo 1 or is something wrong. Is there a way to tell if the gas or filler...

[zx1200r]

My welding text book states that DCEP tig has a stronger cleaning action then DCEN, so I wanted to see if it made a difference.

[zx1200r]

How do I change the default tig setting to DCEP + ?

[zx1200r]

I have a Dynasty 300 with the coolmate package, its been working good so far with aluminum.
1.I have some mild steel around 3/32 that I was welding with a 3/32 2% thoriated tungsten on DC and it is hard to keep it going, the metal seems to crater and leaves a lot of holes in the weld. I wire...