There is an easier way of doing this, get a small detail decorators roller from a decorators shop, and use Humbrol enamel paint (Post box red) the type that is used to paint model aircraft. Degrease the grill with meths, and Scothbrite area to be painted, no need to mask! load the roller with paint, and give it one very light coat, leave 24 hours, then give it another... the finish will look like its been sprayed, any excess can be removed with White Spirit and a cotton bud.
Thom