On Tue, 10 Sep 2013 05:21:58 -0700 (PDT), Sonny
wrote:

Two-three years ago, we discussed clear coats for outdoor furniture. It was proffered whether the base, for oil base house paint, was good or better than dedicated marine or other clear coats. The rationalle: Since house paint is understood to be appropriate for the outside of a house, the base (no pigment added) should work well for outdoor furniture.... it dries clear.

Two years ago, I experimented with applying the oil base base, no pigment added. In the can, it was opague/milky, yet dried clear. It's the colorant/pigment added, that provides the UV blocking qualities, however, I tried the base, as a clear coating, to see if it would hold up, worked well enough, long term. Initially, I used a Spar Urethane and it held up well for 5-7 years. Two years ago, I stripped and refinished it with the oil base base. Here's the project, Mom's swing, to be hung under an oak tree.

http://www.flickr.com/photos/43836144@N04/4035599544/

This above oil base base finish did not hold up well, at all. It quickly deteriorated and turned black, as if the oil solvent biodegraded. Lesson: Do not use an oil base paint base for clear coating outdoor furniture. Also, it was a pain to strip off, clean and/or prep, for subsequent refinishing/painting, especially after it had deteriorated/blackened, as it had.

Update: Recently, I decided to paint the swing, rather than clear coat it, again. A landscape architect advised not to paint it white, or it would stick out like a sore thumb against the natural background. That sounded reasonable. He recommended a dark blue frame and light blue slats. It was primed with Zinsser oil base primer. Here's the result, with the following 2 pics: http://www.flickr.com/photos/43836144@N04/9717812768/ I must have selected the wrong shades of blue, as these colors are not good for this application/lawn scenario. It looks worse in person, as opposed to the view in these pictures. I'll spray paint the swing some light/moderate green color. Lessen: Blue is not the best color for this sort of outdoor furniture.

Sonny

Fine Woodworking ran an article on outdoor finishes in issue 205.

They tested Watco Exterior Wood Finish, Zar Exterior Poly, Man O' War
Spar Varnish, Epifanes Marine Varnish, and Smith & Co. Penetrating
Epoxy Sealer under the Epifanes, and had samples sent to several
locations around the country to be outdoors for 1 year.

Only the last 2 samples held up in all conditions, and equally so.
They concluded the epoxy wasn't necessary. The downside is that it is
more costly than other products, and instructions call for 7 thinned
coats. I saw a price of $34/quart and up online.