DD's Airbrushing Tip o' the Day:
Okay, so here's the scenario. You've taped up the painted area's of your Transformer you don't want to be sprayed a certain colour. You spray the new colour after which you then remove the tape. Oh Noes!, you then discover some of the paint has seeped through onto the area's that were masked. If this happens and the paint that was taped is of a lighter colour than the new shade of paint, this can be a real PITA to fix (especially if using acrylics).
My answer?
1. Wait 1 (preferably 2) days for the new paint to properly dry
2. Tape around the area that's been 'graffitied'
3. Veeery gently sand the graffitied area using 1000grit sandpaper (you don't want to sand the primer off!).
4. Dust off the area using your airbrush (use high psi) or eyeshadow makeup brush
5. Respray the area
Done!