Well let's see to answer the second question first, I'm an idiot. Didn't measure out enough wax to fill both molds so I just topped it off with a greenish black, turned out more black in the pic. My camera sucks. On the others it's where the two colors combine after heat gunning them, which doesn't bother me as I think it adds to the look of the candle. No way around it that I know of with how dry I get the wax to hold the marble color. I want more control of the marble so I let the wax get pretty dry. Hope that answers your questions. BTW the green one with the black bottom is in the remelt pile.