Upper surfaces less. The summer sun here can be brutal.

Only thing I've found that really holds up is Acrylic Automotive clear coat, but it MUST be sprayed. Shot the spruce mast with it 5 years ago and it's still good, but the wood under has bleached.

I've been told that Imron has a clear coat, acrylic, that has a UV filter and is brushable. Never used it so can't comment,

Mast after five years, including sometime in keys and Bahamas