[Thomas Dean]

I had to qualify some alumn. weld procedures sevral reays back and we found that a tri-mix gas was the best...92%argon, 6% helium, and 2% sorry I can't remember. But Hillbilly is correct also with a argon/helium mix, and argon is the most accepted shield gas. When welding thick alum., especially 3/8" and up, preheat by first using a flame with little or no oxy., then adjust flame correctly and heat until all the black is gone. Once at this heat you will find the welding is easier and faster.