track types

[jward]

rust on both the top and the sides. definitely caused by the soldering.

[GG1onFordsDTandI]

Ive never had a flux issue, I seldom remove it after. But is everyone aware that flux should be removed with a brush and/or flux cleaner? That some spread over time, like oil. That the heat, chemicals, and corrosiveness of the product can affect metals differently, changing some.
Dampness is more of an enemy than water quickly, and fully dried off of, most any metal. Drying quickly, and fully is the key. And Ive run motherboards through industrial dishwashers (no soap, etc.) time and time again with about a 1% failure rate to water.

As a note, On another forum someone once used Simple Green to clean his plastic roadbed track (of a different brand and scale, but high quality) From what I gather, soon after the track rusted, pitted, and flaked apart. Another said it softened his plastic.   "Applier beware" 

[jbrock27]

I do make a point to remove any leftover flux, after the job is done, with a rag.  Sometimes with some alcohol as well.