Friday, May 11, 2018

Some Details About Weathering Ballast Hoppers

CN orange ballast hoppers develop over the year a peculiar weathering pattern. Most pictures from various eras show them with a distinctive occurrence of rust pitting and abrasion on panels, keeping the ribs rather pristine. No streaking seems to play a major part in the weathering process but only a typical accumulation of dark dirt on the ends and under body. My I don’t know the real process behind the rust pitting, I wouldn’t be surprised it is the result of loose ballast stone dropped against the panel when the cars are loaded. To further my point, you will also remark the top horizontal stiffener is also quite rusted in the same central area while in good shape at the car ends.

Top: unweathered, bottom: with filters and weathering (yellow hues can be seen)

To replicate this neat effect, I decided to first fade the orange paint using a yellowish-tinted filter. Filters are used to alter the base color. While model railroaders have a tendency to completely fade a model, military guys generally do it by panels in a more controlled fashion. Different tints can be used to add variation and create steel panel buckling (modeller Tom Johnson is well-known for using this method to create hyper-realistic grain hopper weathering). In the past, when I weathered the initial fleet of Harlem Station cars, it is a method I used intuitively and which I thought brought far better results without having to flood models with heavy washes.

Light weathering and yellow + burgundy filters

Once the color is altered, I came back with the airbrush and added a very subtle coat of thinned rust paint where the pitting effect was the most obvious. From various pictures, it is possible to see rust leaching out of the pits, creating a muted coat of rust powder over the intact paint. When it was dry, I splattered thinned burnt sienna oil paint over the rusted spot until I got an effect close to the prototype.  Once done and dry, which didn’t take too long since I used very little solvent , regular weathering techniques were used to pop details here and there or add some dirt.

The interior is yet to be painted and weathered independantly

I previously said I wasn’t interested in replacing the grabirons and that I would take care of their appearance during the weathering process. To make them appear thinner and more prototypical, I weathered them heavily until they were almost dark brown. When dry, I used a brush loaded with Tamiya airbrush cleaner (or any other strong solvent) and cleaned the grabiron face to bring back the color. The result was a thin orange line while the thick plastic section remained quite dark, making it disappears.  It certainly doesn’t beat metal grabirons, but it definitely helps to conceal oversized molded on details. Also, if you look at prototypical pictures of CN ballast hoppers, it clearly appears the grabirons keep their bright paint in stark contrast with the dirty surrounding steel components.

Finally, a protecting matte coat was applied. This time again, I didn't follow the normal recipe but added a light tan tint to the mix before airbrushing. This helped to blend all the weathering effects together while brightening the overall model as if it was under the sunshine. It is well known we have to take in account that color does indeed scale and this is a good moment to do it with this last control coat.


  1. Hi Matthieu:
    Your weathering looks great. Can you tell me more about the tint filter you used. The products make and how it is applied...George Dutka

    1. Thanks for your good words George. I'll do it in a follow up post.