I have done lots of color filling and finally mastered it. First, the
marking must be quite deep and without a burr.
Clean the object well by dipping in acetone or naptha. When dry apply
the laquer of choice.It can be pretty heavy.
open up an old white pages phone book
and blot the surface ink off. Just press it down, move to clean spot,
repeat until only a very thin film is left. ley dry overnight.
Take some scotch transparent tape and lift off that residue. If that
doesn't quite get it use auto wax and a soft cloth to finish it up. I
like KIT liquidwax