[fred cook]

the ultrasonic cleaner. I don't think you will find any paint that will stand up to that kind of process except maybe an epoxy based paint. An alternative could be to polish the rear edge of the front sight with an abrasive so that you would be looking at bright metal. Of course, that process would be permanent. You could repaint the sight and then not clean it ultrasonically. At least you have a couple of choices on which way to go! Good luck!