Since my layout is all Atlas O track & switches, I simply sprayed EVERYTHING, i.e. both sides of all three rails, switches, ties,,,,,everything. After about 10 to 15 minutes of dry time, I used a piece of 1X2" lumber, with a cotton "red rag" wrapped around it moistened with Lacquer thinner, and cleaned off the rail tops. I would spray 8 to 10 feet of the main line, clean off the rail tops, then do spray some more. Two days later I would REALLY clean the tops of the rails with 320 grit shop cloth, which also removed the "blackening" on the center rail.