Tim Shoppa wrote:

...
Shellac is another option I suppose, but shellac seems to me to be
something like the enamel coating on magnet wire, and having used this
in rooftop antennas in the past I was quite surprised that in the
summer it gets hot enough up there to burn off the enamel.

Spar varnish seems to be the ultimate in wood coatings for weather
resistance.
...
Tim N3QE

If those ancient OT's heard you state the above, after desiring
materials better than dehydrated wood with hydrocarbons for
preservatives, as their insulators ... well, just suffice it to say,
they'd strike you up the side of the head, HARD! grin

Regards,
JS