Steve:

I've just finished painting a 30' sailboat hull with two-part
polyurethane using foam rollers, and learned a lot along the way.

I was reluctant to even consider spraying the paint, since I have no
experience with spray equipment, and because of the potential health
ramifications.

The suggested method of manually using these products - regardless of
manufacturer - is generally known as the 'roll and tip' method,
whereby one rolls on a small (say 6 sq ft) area then immediately
'tips' (lightly brushes) off the roller stipple. I began by
attempting to do this with the Epifanes two-part polyurethane, with
results similar to what you seem to be experiencing, i.e. remaining
brush marks (my environmental conditions were 80 deg F @ 50 % r.h.).
Unhappy with the results, I sanded off the Epifanes, taped off the
boat's transom into 3 similarly sized areas, then applied Awl Grip (US
Paint) to one area, Interlux two-part the next, and the Epifanes
two-part to the third, all using identical equipment, and within a few
minutes of each other. The hands-down winner was Awl Grip, which had
just detectable remaining brush marks. The Interlux was second, and
the Epifanes third (in my opinion).

I subsequently was turned on to (via this forum) what I now call the
'fridge' method of applying this paint. CAUTION: This method worked
for me using Awl Grip Off White, and may not be applicable to any
other paint/color combination or in different temp/humidity
conditions.

By mixing up the base/reactor/reducer the night before application,
then covering and placing in the refrigerator (about 8 hours between
mixing and use), the Awl Grip was applied using only the foam roller,
with INCREDIBLE results. Flow out was excellent, zero roller stipple,
zero brush marks, in short a "sprayed" result without the sprayer.

I don't know if a foam roller is applicable for painting a Rolls, but
if you ever need to paint a boat hull...

Mike Worrall
Los Angeles