Adding polyester-base pigment such as the glass suppliers stock will give you complete opacity at about 2% concentration, which will not compromise the strength of the epoxy. But this will not solve the UV problem. Trouble is that the UV will degrade the surface, causing chalking, crazing, and checking, leading to failure of the waterproof integrity of the glass and wicking moisture along the strands over time. Additives in the epoxy will not prevent this condition. Some kind of UV-resistant topcoat is necessary, either a clear varnish or a pigmented coating.

2-part polyurethane gives the best performance, adhesion, abrasion resistance and durability, but can be tricky to work with and contains lots of hazardous solvents. I happen to like it a lot, and used it on one of my boats. If you pay attention you can get a nice finish with brush and roller. Interlux comes to mind as one manufacturer, and there are several others, check with your local marine supplier.

: I'm far enough along on my s & g kayak to start thinking about paint.
: I've read some good things about two-part polyurethane, but I don't have a
: source of supply and I don't know if it will be available in the color I
: want. (I have my heart set on Tweety Yellow). So my question is,would
: pigmented epoxy used as a final coat degrade from UV? Would the pigment,
: used in sufficient quantity to produce an opaque coat, compromise the
: properties of the epoxy? What say you all?