Final chapter of this project. I weathered both boxcar recently using various mix of acrylic paints to fade the color, oil paint washes and weathering powder.
The first car was heavily weathered according to a prototype picture. Cement is a messy commodity to transport and if you look at cement cars - whatever their type - they aren't looking pristine.
On the other hand, the second car is less battered down and represent a boxcar that was repainted quite recently. I like to vary the degree of weathering from car to car. It really brings life into a freight consist.