Hello name is Duke, I am an experienced welder, but new to tig welding. I am trying to practice on aluminum. I'm running 100% argon 20 cfm. 2% thoriated tungston and pure. I can start an arc on DC, but I'm having such a hard time lift starting on ac. I'm using a foot pedal and welder is set to 100 amps. Once it starts I usually can keep it going for a bit, but nothing like DC. Am I doing something wrong?