I'm working on a lindberg diesel tug and so far it's gone pretty. I would like to wind up with a semi / low gloss finish. The paint as it is now is a little too glossy. I was thinking of a final spray coat of dull and then buffing it a little. Is this the best approach or is there a better way?
For the final finish I use Xtracrylix acrylic varnish exclusively these days. For a low gloss finish, I spray the whole thing matt and let it dry for at least 24 hours. Then I mask off the areas that need to remain matt and very lightly spray the satin varnish on the gloss areas. You can spray more mist coats of the satin varnish on until you get the depth of shine required.
Do you have an airbrush? One can do semigloss with rattle cans, but it is harder.
If you spray a matt paint very wet, it will go semigloss. If you spray a gloss paint with a very dry coat it will go semi-gloss.
For an existing finish, try airbrushing a VERY thin coat of Testors dullcoat. Dullcoat is a bit funny. It is very hard to get a wet enough coat of it to make a resulting semi-gloss. So it is hard to get semi-gloss on an existing gloss finish.
One thing to try is polishing cloth. If the existing coat is too shiny, going at it with about #1000 sandpaper, or #1000 or 1200 polishing cloth will dull it. You might also rub it with pumice stone powder.