Here is how I add black tips to my paddles. Sometimes just the tip but in this case I applied the black to a large area to hide a defect in the wood. It turned out rather nice looking. Up close you can see some thin areas where some wood shows through. The tradeoff is the more you put on the paddle the heavier it gets.
I first mix in black ink (a permanent marking ink) into wood flour. Let it dry and then I have a nice black powder. I coat the area I want to color with epoxy, then shake a bunch powder over the paddle and let the excess fall off. Do it again and this time I give it a light brush to smooth it out a little, trying not to smudge the epoxy underneath. Then I let it dry. Depending on what I am trying to accomplish I will either sand lightly and then apply additional coats of epoxy, or for a deeper black, I'll repeat the epoxy and powder routine, maybe a couple of times. I haven't tried just staining the wood with the ink but that might work too.
The Connyak BBS