This is almost a repost, but maybe I'll have more answers on single questions.
When tig welding aluminium with AC, I can see the cleaning action of the arc: the piece becomes shiny. However, as soon as I reduce the power of the arc (say, using a foot pedal because I do not want to blow through), I see that the shiny patch size is almost immediately reduced. Is it normal that aluminium that is cleaned by the arc oxydises again as soon as power is reduced even under the argon shield?
Thanks in advance for your help.