It's pretty easy with a bit of practice and a light touch.
This is how I do it, and as there's more than one way to skin a cat... YMMV.
- Make sure surface is completely oil free and dry.
- Fill the rollmark with enamel. Don't try to do a long rollmark all at once... do it in sections if possible.
- Remove the excess enamel around the rollmark with a acetone dampened Q-tip.
- Put a small amount of acetone on a lint free, fine woven cloth or smooth paper towel (I use those blue Scott brand shop paper towels) wrapped around a straight edge (I use a 6" steel machinists ruler).
- Use the edge of the towel/ruler combo and "scrape" off the excess paint. Use the towel edge for one pass only, then move to a clean section and repeat as necessary.
- Go over the surface with fresh toweling and acetone as often as needed to remove all excess.
Too much acetone and it will "flood" out the rollmark. Too little and it will smear instead of remove the excess.
If the toweling is too course or fibery, it will dig paint from the rollmark.
If you screw it up, flood it, remove the enamel and start over.
Once done, allow to dry overnight.
Yellow enamel filled H&K P9S .45 Target.