Soft lead is just another way of saying clean lead. Used wheel weights for example are not "soft lead" as they have all kinds of impurities mixed in. You can still pour decent sinkers, jigs, bottom bouncers etc...but you'll get more rejects than you would with soft (clean) lead. Most of the impurities in dirty lead will float to the top as the lead melts and can be skimmed off but beware...the more you handle hot lead, the greater your chances of hurting yourself or someone near you. This is not boiling water. Lead won't drip off your skin....it'll stay there and burn its way through.