Maybe a year ago, there was a discussion, here, regarding using a
paint base, without the tint added, as a clearcoat finish on an
exterior project. This past spring, I stripped and refinishied a
swing with 3 coats of Olympic Fast Hide Ultra, Int/Ext Alkyd Gloss,
Base 5 - #218156 (directions on the can- "Must be tinted").... no tint
added.

I don't detect the finish, itself, failing, yet, but it sure has
blackened with mold/mildew, horribly so. When new (I made the swing),
I had finished it with Spar Urethane and there was no such molding/
mildewing/blackening build-up in the 5 years the Spar Urethane was on
it. The swing has always been hung under the same oak tree and pretty
much completely shaded, so the Spar Urethane held up well. The swing
is made of ER Cedar.

I'll clean the swing and see what the finish looks like, under the
black. As of now, I would not recommend using a paint base as a
clearcoat finish for an exterior piece.

Sonny