Mike Coslo wrote:
Jeff Liebermann wrote:
On Sun, 25 Jan 2009 20:46:28 -0500, "NoSPAM"
wrote:

For ultraviolet protection, a small amount of titanium dioxide may be
added (1 to 5%), but the microballoons will do a fair job alone.
Painting the finished insulators with acrylic paint (Krylon®) will
also provide good UV resistance.

I've never seen any white antenna insulators (except porcelain). Most
of the plastic antenna insulators I've seen are either black or
sometimes blue. I presume the filler and coloring used are something
something other than titanium white. Yet, everything made from marine
fiberglass is bright white, presumably doped with titanium white for
UV protection.
Is there any benefit to the white color over something like black
graphite stiffener and fill, which also offer UV protection? Duz the
color make any difference in preventing polymer chain breakage?

Drivel: I've noticed that the white PCV electrical tape I sometimes
use to wrap coax and connectors seems to last longer than the same
tape in black.

This is an interesting question. I have UV resistant rope that is black,
as well as UV resistant Ty-Wraps - also black in color. Wonder what the
deal is here?

- 73 de Mike N3LI -
Carbon black (and various other things) are also used as UV blockers.
Obviously, carbon black may not be the best thing for an insulator.
Sometimes it works, sometimes it doesn't. You have to test it.