Vintage Windmill and Wind Generator Forum

I don’t know the brand of varnish they used. Literature and documents I have just say “high grade weather proof varnish.” Three coats were applied and the first coat was allowed to dry 3 days before sanding.

I've always seen spar varnish called out by a lot of manufacturers in their manuals. What brand they used back in the 30's & 40's, I don't know, but I've had really good luck with Rustoleum's spar varnish holding up and keeping a high gloss for many years on props that have been outside but not running.