Touching Up By Hand

[verhoevenc]

Hi, I'm trying to get this design painted over part of a guitar I'm building. However I can NEVERg et a PERFECT edge from masking, either the white seeps a bit, and then I re-spray the edge with red to fix it up... and then the red seeps. It's driving me crazy. Either way, so I've decided to leave it how it is and paint the final touch ups to perfect it by hand. HOWEVER i sprayed some white into a cup and it's really thin and doesn't accomplish much. So I'm gunna go to a paint place and attempt to color match it. However I doubt they will have nitro HAND paints. So I'm wondering what kind of hand paint I can use ontop of nitro, and then also under a nitro clear coat, that I can get at any old art supply store?

Chris