Did you remove the rust first or paint right over the rust?

 

Ha, I'm a lazy bum. I just used packing/newspaper to create a shroud around the caliper and rotor (protect the car paint) and tape on the studs and sprayed. Might last longer if you sand the rust off, but so much more work than just painting again in a year

Note: You need to rotate the rotor the make sure you get all angles and the parts that are covered by the caliper.

 

here are my results, for judgement:

 

Hate to bump back up what was essentially a dead thread, but I searched and came across this thread which was unique to the other solutions for rusty brake rotors. I just wanted to double check before I went out on where exactly the contact area is on the brake rotors?

 

Just mask off all the pad contact area except the most inner 1/4" all around, then the pad will scrape it clean and leave a perfect painted area that the pads won't touch. Also be sure to paint the outside edges (where the vent fins are as these can rust pretty good too).
If you want other colors VHT Flameproof is a good extreme temp paint, much better for rotors than caliper paint or engine hi temp paint. During aggressive bed-ins the rotors will get so hot that those other paints will just vaporize and just about become worthless.
Here's the Flameproof
http://www.vhtpaint.com/products/flameproof/