I've used the "Glow On" sight paint with long lasting results.
The paint recharges the best with a UV emitter ( but a High intensity flashlight does good too ) and are initially 2 - 3 X brighter than tritium for a couple of hours and fades down to barley visible after about 6 hours.
Just scrape out any remaining old paint with a dental pick, wipe clean with alcohol and apply paint. Use a hair dryer to heat up the sights to aid curing. After thoroughly dry, coat with clear nail polish & the pair will last without collecting soot or powder residue.