if the black is in recesses, I have cleaned the part ( laquer thinner), sprayed the black, after its almost dried, wipe the high areas you don't want black with laquer thinner. be careful not to have the rag too wet!!
I've done that too. It helps for some items to cut a slit in a piece of paper as a mask, spray it, then wipe the overspray with thinner. Ex. The Barracuda tailight housings, the front grill shells.
