Bright and shiny trains look out-of-place on almost every railroad, even on the real thing. A working railroad has no time to shine freight cars.
Few cars, or locomotives, are ever bright and shiny, except the day they roll out of the factory or the paint shop. Within a very short space of time all locomotives and rolling stock acquire a veneer of grime, soot, dust, rust, dings and other weathering that gives them that ‘lived in’ look.
When weathering I use many mediums to achieve my desired outcome. Each is discussed in detail on this site. You can read more by following the links below, or using the menus above.
There are many other pages on the site under the weathering umbrella. Use the links in the menu to follow your interest.