Yes, a diluted india link wash should work although if it beads up it can produce odd effects.
Also take some charcoal (not from the grill particularly if it is the kind with lighter fluid mixed in, but the real stuff from an artist's supply store) or even fireplace ash (again not stuff from the grill with food grease on it) and powderize it, then rub it on the plain ties with an old toothbrush. You'll quickly get a slightly darkened and slightly irregular look that is pretty much what you want.. The nice thing about powder is that it is rather easy to "undo" if you overdo it. Concrete ties don't seem to get too dark, but they do stop looking regular and identical after a few years.
Dave Nelson
I would try a wash of alcohol and black India ink for weathering it.As for fastening it down, you could either glue it with Clear Acrylic Latex Caulk, or get some small spikes and spike it down like the real railroads did. I have done both to flextrack with success.
Elmer.
The above is my opinion, from an active and experienced Model Railroader in N scale and HO since 1961.
(Modeling Freelance, Eastern US, HO scale, in 1962, with NCE DCC for locomotive control and a stand alone LocoNet for block detection and signals.) http://waynes-trains.com/ at home, and N scale at the Club.
I have some atlas code 83 with concrete ties and wondering what is the best weathering method with out an airbrush if possible, as I do not have one. Also since this is atlas track, what is the best way to spike it instead of using track nails
Nathan
Cambridge, Ont
B & B Railways - "Connecting the North, one rail at a time"