the paint trijicon uses to outline their vials is a 2 part Sherwin WIlliams paint / Polane hardener that has to be mixed just prior to application. the paint is white in color and the hardener is clear and has a work time of about 4-5 minutes. When the vial is inserted into the sight it is glued in place. Then the paint is applied with a toothpick and the excess is wiped off with a paper towel damp with acetone.

I have had some success with ultrasonic cleaners cleaning the white. You can also try a new brownells parts brush dipped in acetone - scrub vigorously.

Mark