So I finally went and bought a new tig torch and hose. (My old one was in bad shape) Anyways, inside the box was a free sample Tungsten. It's got a purple tip. The pamphlet with it says it can weld AC or DC. I know there's all kinds of color codes for differnt stuff, but I've only ever used red for steel or green for aluminum. Has anybody used the purple? Im not sure if this is right, but I've only used AC for aluminum. So when they say AC or DC, does that mean you can weld aluminum or steel with the same tungsten? That would be nice.