1. Take grill off car.
2. Rub grill down with some fine wet/dry paper (800-1200 grit) it needs a good key ALL over
3. Clean the surface thoroughly with Pre=paint/thinners etc
4. Primer (white/red/grey) depending on your final colour. 3 coats of primer, leaving around 1/2hr between each coat.
5. Colour, again 3 coats with a good 1/2hr between each coat
5. Clear lacquer, You can never have too many coats of lacquer, but again, at least 3, but in an ideal world, the lacquer should go on 24hrs AFTER the last coat of colour, to allow the colour to harden properly. As its a small area, you would get away with doing the sanding/cleaning/primer/colour in the morning, and leaving to harden, then put the lacquer on in the evening.
6. Put the grill back on
