If you are painting metal then it's a good idea that you use a paint that doesn't 'eat'/destroy metal. If it bonds to metal then it becomes a part of the antenna. No big deal unless you put it on so thick that you bend the thing, sort of self defeating, huh?
It's a good idea no matter how 'conductive' the paint it (or isn't) that you not paint the insulator parts of antennas. I'll bet you can think of why that would be.
How about non-metal antennas? Personally I would use a non-conductive paint. Or maybe just epoxy it, of refinish with a layer of fiberglass 'goop'.
There have to be several 'good' reasons to paint an antenna. In most cases, if it's to protect metal from tarnishing it's a waste of time. That 'tarnish' only affects the antenna's looks. If it's rusting out, then I think it would probably be a good idea to replace the thing and 'seal' it to start with, rather than try to extend it's usable life much. That assumes you can afford to do that, or there's another one available, of course.
I painted an antenna made of copper. Why? Because I got tired of looking at tarnished copper, no other 'good' reason. Didn't help/harm it's performance that I could tell, I just didn't have to look at it anymore. That a good reason? Beats me, but it made me happy.
Make your self happy as long as it doesn't cause problems. What if it causes problems? Don't do it anymore...
- 'Doc