i used solar flux on ss tube all others i just tig with no purging with gas as never seen a need for it .i tig for many years i am far from the best but far from the worst the other guy in the shop is abit better then me he tigs more then me he never purgs with gas and his stuff is flying up in the air. i do not do it as cost to fill a tank of gas is $$ i can not see using any more then needed