Clear coat will help. I've been having good luck lately having all of my hardware "clear zinc" coated and then paint them for the correct-appearing finish.
First you have to have someone media blast the hardware with glass bead, then take them to a plating company and have them "clear zinc" coated. It's a wet process that has replaced silver cad plating.
There are a ton of platers in Michigan. I use one in Flint just a few miles from the house. He does "government jobs" on the side. A coffee can full of fasteners usually runs about fifty bucks.
When you refinish your hardware are you getting all of the rust off before painting?
