I’ve been using Birchwood-Casey “Super Blue - Liquid Gun Bluing Solution” for several years now on Fruil, Spade Ace and Master Club metal link-to-link tracks. It’s just much easier to find locally in pretty much any big-box retailer or sporting goods store. Price is comparable to, or even slightly cheaper, than most proprietary modeling “burnishing” fluids.
The actual result is somewhat variable from one set of tracks to the next even within the brand lines. However, it generally turns the tracks a dull, brownish black in all cases.
BTW, I can’t seem to notice any real difference between their “Super Blue” and their “Perma Blue” and have used both with the same general results.
It MAY help to pre-wash the track sets in a strong detergent like Simple Green before trying to chemically color them.
FWIW, here’s a shot of my T-44 tracks initially colored with Super Blue. I consider the chemical coloring to just be the first step in weathering tracks, though.
