'smoke'

[guest311]

not sure if this will be of any interest / help to anyone, but for many years I have used pencils to 'colour' the windows on firstly white metal kits, and then on 3D prints.
so, primer, paint, pencil in windows, then varnish to seal / provide base for transfers.
I have now received a bottle of Tamiya 'smoke' acrylic paint, and tested it on a 20mm 3D printed gs truck's windows and windscreen, and it seems to work fine.
the advantage, especially with wargames models which may need camo schemes, is that where pencils didn't seem to work too well over several coats of paint, so you needed to base coat, then pencil the windows, then add camo scheme around the windows, using 'smoke' might make the windows the last item painted and so easier to paint the camo schemes.

as I say, may, or may not be of any help in N, but might be worth a try.