Use enamel paint. Just a jar of gloss white and small brush. Testors enamel will do. Wal-Mart, Hobby Lobby, Micheal's Crafts or any Mom and Pop hobby or hardware store will have it.
That is what I use when I refinish firearms with fixed 3 dot sights.
Just degrease the sight with acetone, rubbing alcohol or thinner. Let dry, touch it up.
Do all 3 while you are at it. I like using gloss white, because in sunlight they are easier to pick up and in the case of the front sight, the carbon deposited there by the muzzle blast wipes off easier than the flat white.
As for sights, I'm fond of the 10-8 Performance rear-no dots-and a tritium front.
I used this front sight from Bowie Tactical, a Ameriglow front-
ameriglobowietacticalmandpSights
This rear sight from 10-8-
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