I love thin, clean panel lines done with a technical pen and black ink. However for realism this doesn’t work too well. Now generally people will use a “wash” to fill in panel lines. A wash is done by brushing very thin enamel paint into the crevases, then wiping the excess away with thinner. It’s a very mess process and doesn’t allow much room for error.
I like to use my koh-i-noor technical pens for panel lines. The lines are crisp and smooth, and allow you to get to deep areas cleanly. At first if I screwed up (went out of the lines) I was screwed and had to repaint. I discovered though through trial and error that there is an easy way to use the pens which allow for many screw-ups.
Black Lines »
First, paint your kit, then give it a coat of Future Floor Acrylic sprayed through an airbrush. When that is dry completely (24 hours) use the pen and ink your lines. If you go out of the lines, dip a bit of paper towel in a solution of water:409 (70:30) so that the towel is just barely damp, and wipe away the mistake. Easy!
Faux Wash »
Now for the look of a wash. Koh-i-noor makes colored inks. For my martian Zeta + I used a mixture of red, orange, and a drop or 2
of black to make a brown. I filled my pen with it and used the same method as above. The only difference is that instead of wiping with the 409 solution for mistakes only, you do it to all the lines to make it look dirt encrusted. That’s all there is too it. You could potentially make any colored ink for the washes.
Mix your inks and fill your pen. Test the color out on paper with a paintbrush beforehand.
Ink your lines on your piece. The piece should already be painted and have a coat of future on it. Notice how I went out of the lines and wasn’t very neat.
Finished piece is cleaned up with wad of paper towel and 409 solution. The end result with the brown ink looks like a wash.
When your parts are inked, give them another coat of future before decaling as the water from waterslide decals will cause the ink to run and make a mess.