So, I think I'm almost at the end of the priming, and getting ready to put some colour spray on.

The finish will have red on the edges, black on the top. Hoping for a nice clean line between the two.

What approach do people use for masking off areas while doing other colours? Do you mask when spraying the first colour? Or do you just spray the first colour, knowing that it will get covered with the 2nd colour?

I've been experimenting on a bit of scrap, and found that if I mask off and spray red, then remove the tape, mask off the other side and spray black, then I will get an obvious line where the edge of the red paint was. It leaves a raised ridge - I guess the red paint has raised up a bit where it can sit next to the tape while drying.

Should I have lightly sanded down the edge of the red to remove that ridge before spraying the black?

Or should I just not mask when spraying the red edges, let that dry, then mask off the bits I want to keep red and spray over with black.

Any opinions welcome.

The tape I have is professional painters tape, for use with spraying, varnish, lacquer, etc, with 10 day clean removal. It sounded convincing to me anyway.