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I got this question from a friend and don't know how to advise him.
He added, "All I know so far is that I need a paint with no metals in it. I also know that most white bases have a whole lot of zinc."
Furuno advises: " Yes, it is okay to paint your radar antenna. However, the paint MUST be epoxy-based with NO metallic ingredients. Paint with metallic ingredients will cause poor performance and possibly damage to your radar."
https://www.furunousa.com/en/knowledge_base/general/painting_a_radar_antenna
But when I look at the SDS sheets for Petit EasyPoxy, it's darn hard to know which ingrediants qualify as "metallic".
My friend is looking for a white paint that won't cause trouble, by the way.