"W Canaday" wrote in message
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BTW, spar varnish is a phenomenally bad choice ... it is intended NOT to
dry for a long time. But eventually, even spar varnish will dry.


Suggest you consider an ordinary wiping varnish instead and just call it
a day.

Spar varnish is long on the oil component for the flexibility it will
require to survive fluctuations in temperature outdoors. It also normally
includes an ultraviolet inhibitor for the same reason - it's outdoor
varnish.

Since it is a long oil varnish, it will take longer to cure than standard
varnish, but not as long as if it were strictly a curing oil. Save that the
greater amount of oil versus resin makes a softer film, it is perfectly
suited to the task of keeping moisture out of the wood. Your best choice?
Maybe.