4226-55mL Super Corona Dope

https://www.mgchemicals.com/products/conformal-coating/varnish-for-electronics/insulating-varnish/

4226 is a highly insulating varnish with excellent arc and corona resistance. It is a low viscosity, 1-part coating that is easy to use and adheres well to many substrates.

This PCB varnish coating protects transformers, coils, motor windings, and various electric generator parts against arc, corona, corrosion, and moisture.

Features & Benefits
High dielectric strength – 4 100 V/mil (dry); 3 000 V/mil (wet)
Excellent moisture resistant
Excellent finish – tough, flexible, glossy, and durable transparent coat
Good adhesion