[Paul F]

I'm looking for some help on aluminum TIG welding. I've searched the web but not found what I'm looking for. I don't seem to be able to consistently get a nice clear puddle. In fact, I rarely do. Most times, the aluminum has a slag look to it when I heat it up rather than a nice clear liquid puddle. I figure I'm not cleaning it right. I've played with the gas flow, frequency, to no avail.
Can anybody tell me what I'm doing wrong or point me to a site?

I'm using a Miller Dynasty 200.