Painting - How do I paint radiator grills?

I have baseboard hot water heating. The hot water pipes are covered by the standard white metal covers. After 15 years, they are in need of a painting. I understood that you can use latex since the hot water pipes don't make the cover hot enough (from an earlier post). I am using semi-gloss latex paint with a brush. The brush marks show up on the metal even after two coats. Should I be using a spray can? If so, do they typically come in semi-gloss white? There is also some rust spots. Thanks

GreatHusky, Brush marks that remain when using latex enamel is normal and is one of the greatest drawbacks to latex paints other than flat. If metal is at all warm the marks will be all the worse. Spray paints do come in semi-gloss and of course if you go with that there will be no new marks but any that may be there now will surely show. Whatever paint you use remove rust with a wire brush and spot prime with a good metal primer and if badly rusted spot treat with a rust converter. The answer for you may be to move to an oil paint because it is self leveling and shows little if any brushmarks....Mike