No, I didn't Lou. The powdered stuff won't be a problem, they'll be solid black, not concerned there at all. The resin on that stuff turned black with the finer dust.
The chunky blanks, we left the tube natural with hopes of a few odd spots of gold color popping through for contrast. Pretty sure there is enough chunks in it that it's going to be covered almost solid however. One article we found on it, suggested pouring the blank in that fashion, so we're experimenting with those two. Should have 6 blanks to play with total, which would give Marc enough for 12 pens if he wants to turn that many of them, if one or two don't work, we aren't out a lot. And, I have an excuse to pour more of them!
Stuff really is fun to pour, no fuss, mix it up, pour it, and walk off and leave it on the counter. These two came out black and shiny, and appear flawless, just like the others.