If the strength of the epoxy is important, do NOT color it dark, at least
not if it will be in the sun. Dark colors get hotter and the epoxy loses
significant strength at even mildly elevated temperatures.

Military uses; e.g. fighter aircraft skin, involve epoxy that is oven cured
to withstand higher temperatures -- a touchy process and a major investment.

Roger

http://home.earthlink.net/~derbyrm

"Dave W" wrote in message
...
I don't know about the degree of UV protection offered by tinting. In
terms of how dark can one tint, I have added black color to make the epoxy
as dark as ebony. By the way, I have had a test sample of epoxy and
fiberglass scarfed plywood in the bed of my truck for four years with no
apparent loss in strength of the joint. The (clear) epoxy has yellowed a
bit but the joint seems to be very strong.
Dave