Hm. If titanium doesn't take paint, what about nail polish? I mix glow in the dark (GID) powder with clear nail polish, and I'm considering painting the top of my stakes with that. This is the long-lasting GID powder, it goes for 8 hours. I have also painted the inside rim of my flashlights with it (on the edge of the lens). When the flashlight is on, the GID powder gets charged up.