when you heat it up to molten the impurities will come to the top (dross). a pea size piece of pure beeswax will help get the dross to come to the top. skim it off and keep stirring until it is all gone make sure when you are using WW that you are getting just the lead ones and not steel or magnesium as this will ruin your formula. the learning curve is not steep if you see it done - watch a youtube video and be careful and you will be fine. I powder coat afterwards to keep from having to lube the bullets- i still run them thru the sizer afterwards.
Sixshot is the expert here and was gracious enough to answer some PC questions for me.