Static wicks

Is it permissible to paint static wicks? If so, what characteristics must the paint possess?”

I would say no.

Static wicks discharge electrical potential differences between the atmosphere and the aircraft.

They are designed to dissipate electrical charge in a slow controlled rate instead of a quick "pop" (like dragging your feet on carpet in a dry environment and then touching a door handle).

A slow discharge keeps static interference on voice communications to a minimum.

I have never seen wicks painted on commercial, corporate, or piston-popper aircraft.

Paint would interfere with the wicks ability to perform its job.