I've hand painted many calipers over the years and never had an issue with any. I do not recommend using my procedure if you are going to track the car. Last job I did was my XLR last year, I just use artist type brushes and take my time. When dry, I use a sanding block to clean any excess paint from the raised lettering.
I use a very easy to apply and sturdy enamel pin striping paint by "One Shot", comes in many colors and in half pint cans. It can be acquired through Eastwood Auto Restoration Supplies.
The original color of calipers were silver, used a maroon color to match finish. It turned out excellent, no brush marks, paint flowed out to a smooth and glossy finish.