Welding Tips and Tricks

I'm and OLD newbie. I have tried just about everything and I'm fair at most things. Been watching a lot of Jody's pretty welding and thought I might try my hand at TIG. Bought an Everlast Multi unit with DC TIG. Have been able to make coins most of the time. Learned why TIG Fingers are so valuable. I own a couple and may get a few more. My experience so far TIG welding leads me to wonder if my Argon is contaminated. Although it has been relatively humid in KCMO and from what I read that can affect things too. So I'm wondering if there's a way to tell if your argon's contaminated. I bought the tank from a guy who sells them locally and indicated it was filled with 100% argon, but how can one tell? Recently I took an old auto Brake Rotor and hit it with a disk sander to a nice finish. I was using the hand switch for the first time so I could set the amperage and gas pressure. I lit up and started stacking coins (I wont call them dimes.. more like a pocket full of change) with some ER70S-2 filler and when I let go to view my masterpiece it looked like a blackish/copper colored soot had settled over it. I could wipe it with my glove and underneath was a pretty nice weld (my standards) not pitted or anything terrible. At the time I was using a gas lense and a #7 Stubby cup, about 100 AMPs, 3/32, 2% Lanthanated about 1/2" out. Well how's that for a follow the leader post Jody? Now what's wrong with my setup?

Hello and welcome! A half inch might be a bit long on the stick out. But I'd guess it's got more to do with the rotor metal being embedded with contaminates from the brake pads than a gas issue. Hard to say without a good pick of what the soot looked like and how it formed on the weld.

Your brake rotor is most likely to be cast iron. Now you're in a crap shoot that experienced welders often curse at and you are using the wrong filler for cast as well. Why don't you stay with low carbon steel for practice and skill development.

Welcome...

thanks

Just following up on this.. it turns out the Argon was not pure and allowed oxidation too. While the cast issue was also true. After running a few beads on mild steel with the same problem, I finally turned in a 1/2 full bottle of bad argon for a new bottle of good argon and the difference proved the matter. Thanks for each of your input.