Looking good! At some point I need to try dipping a flyback in Polyurethane varnish and see how it holds up. The Super Corona Dope MSD sheet says it's a modified Alkyd, which I'm assuming means it's a your basic Alkyd resin with Polyurethane additive for better flexibility/heat resistance. Also most Alkyd and Phenolic resins are moisture permeable, meaning they will allow moisture vapor to slowly pass through them.
https://www.alliedelec.com/m/d/f2adb...1b03fa9565.pdf