Thank you! I got this swirl just from pouring colors into the mold- no spoon, no ITP (not really). I poured the black in first (maybe 16-20 ounces) and then poured in 8 ounce cups of batter one after the other, each one having some white and black in it but progressively having more white than black. I didn't really think it would go around like it did and I couldn't tell by looking either. I thought it would be more obvious which cup was which, if you know what i mean.
Jaccart, I used activated charcoal so I can't comment on the oxide but I seem never to put enough in and get dark dark gray and not black, which is super annoying. I finally just went whole hog and made it BLACK. I also never put in enough TD to get that opaque white and I finally managed that too, although I got some crackle, but that's okay. I always think my base will be white enough with a little TD kick-sometimes it takes a long time to find out you are dead wrong!