Jon Elson wrote:

I hadn't found my thoriated electrodes when I was last trying the
aluminum, and was having a HELL of a problem with pure Tungsten
electrodes. I found those Thoriated electrodes, and they made a huge
difference when welding steel.

They would. Thoriated work fine on DC (steel) but NOT on AC
(Aluminum). You need Zirconated or one of the newer types Ernie has
recommended for AC.

Ted