How magnets rust

[bob golding]

rather than try to seal the iron from oxygen with paint  another method to control corrosion is to completely and evenly oxidize the surface on purpose with a chemical oxidizing agent.
similar technique used in gun bluing which i believe turns the surface to iron nitrate

there is a waterborne paint called extend .
as well, there is paint by Benjamin moor called rust inhibitor.
ive used it on antique vehicles and any other junk i want to stop from rusting.
i did both rotors and hard drive magnets a few years ago with it
seem to be ok

the compound  turns the surface into iron sulphide.

i ried  something like that last time. dipped them in jenolite which id simular to your stuff then dipped them in gavafriod. still rusted.
smells like dog poo while it's curing but nothings too good for my windmills.