It depends on the paint your using.
In my case I'm lucky that it can be mixed as a solid, however as we're on water base at work I had to order it in, and it was sent as a solvent basecoat,
Here's a trick though if you mix base with the clear then add activator it will dry shiney, it's the same as the metallic ral colours, however your never going to get an amazing match with silver/grey with touch up it will be very dark,
Another tip is to buy some ultra fine nail art brushes off ebay, there perfect for it, failing that a toothpick will do.
Tomorrow Is polishing day.
Jake