I think the black is related to how long you are smoking.

Depending on the rib, I use a 3-2-1 (spares/beef) or 2-2-1 (baby backs) method- where the middle number is a period of time they are foiled, which will help prevent that.

First number is the initial smoke time, where you can use wood smoke to impart the flavor you want. Second number is the amount of time you have them wrapped in foil, with about 4oz. apple juice and/or beer (or whatever you want) to make them tender and juicy (save your smoking wood here). And the last number is the last 'hour' back out of foil and crisping back up. This last hour may vary from 30 minutes to an hour depending on whether the meat has pulled back from the end of the bone 1/4 inch or so...

I also sometimes add a little rub back on after to add some color and flavor.