Any White Pens/Markers To Write Over Black Pens? I'm just getting into drawing, and I've made a sketch that I would like to fill in with black, red, and white pens (or markers). Since pen is permanent, though, I'm concerned that I might accidentally go a bit into the white parts with the black pen, ruining my drawing. Are there any white pens opaque enough that they could cover up mistakes I might make with the black pen?

Thanks!
I'd try a correction pen, there are now quite a lot to choose from. 

This web page shows over a dozen kinds, and how opaque they are over black ink.

The best white ink pens

Matching the paper colour and white pen might be tricky.