On some miller machines aren't you supposed to use lanthanated for AC?

 

i was taught to mainly use pure tungston (green ends) when doing AC, it resists those little spikes that form. also it really doesnt matter what tungston you use, like the pure lasts longer on AC but does fine on DC but when you sharpen it it seems to snap off good chunks (like 1/4'') but if you use thoriated (red) then it doesnt snap off when you go to sharpen it.

ninja edit, just buy the cheapest ones