Pictures of Harlem Station show the area was extremely dirty. The concrete pads were covered in coal dust and mud while the roadbed was a grungy mess with oil stains.
To reproduce this characteristic on the layout, it is crucial to do a weathering process following several steps.
Following several prototype pictures, I dusted the carfloat apron area with lots of weathering powder to reproduce the very dark and dirty look of the ballast. Following this application, a oil paint wash was applied.
Black weathering powder was also applied over the coal spills on the tracks.
Finally, a very liberal dirty oil paint wash was applied with a large brush over the concrete pads. Prior to this application, I carefully scribed a few cracks to give some texture to the cardboard surface.
This is only the beginning since the pictures show the concrete was far more dirty than that. The soil at Harlem Station must be extremely contaminated!