In the previous four posts on this topic, I showed my materials and process, using house cars (box and refrigerator cars) in a two-part sequence, first roofs, then car sides and ends in a subsequent session. [Here is a link to the fourth post: http://modelingthesp.blogspot.com/2014/09/my-acrylic-weathering-method-part-4.html .] I mentioned in an earlier post that tank cars really cannot be done with those two steps, as there is no “separate” part you can identify to weather differently from the rest of the car, as there is in roofs vs. sides. In this post I address my weathering process for tank cars.
The overall weathering is the same, in that the model is thoroughly wetted with wet water (be generous), then a chosen amount of pigment is applied and spread evenly over the car. The draining downward of pigment, evident on any more or less vertical surface, was described and illustrated in talking about car sides, and here it is even more prominent. Suggestion: once your weathering work on house cars seems to go all right, then try a tank car.
I usually end up holding the car with fingertips at the bolsters, as you have to weather the walkways and trucks, along with the tank and even the center sill. As with any of these methods, you will get a fair amount of acrylic pigment onto your fingers during the procedure, but it comes off easily with water and should not be a worry. You will definitely experience this with a tank car.
Let’s look at a prototype car to illustrate the points to be pursued. This is an SP car, whose paint scheme shows it is in company fuel service. Note the spillage around and below the dome. Notice also that the entire tank is streaked vertically, as rain has washed dirt downward. (You can click on the image to enlarge.)
Also trucks are quite dirty, in a brownish color. The photo is from the Bruce Petty collection.
Weathering a tank car fairly heavily is quite realistic, as these cars often went many years between paint jobs. Here is a Proto2000 model of a Union Oil Company tank car, which I would call “moderately” dirty.
I try to achieve some of the same dirt streaking on the tank, and dirt over the walkways, as is seen on prototype cars, that is illustrated in the detail shot below. The weathering looks uneven in the bright light used for the photo, but under layout lighting this effect is not visible.
Note that walkway and trucks are weathered too, and that a route card has been simulated with a small square of paper on the edge of the running board. On the prototype, these were often stapled or tacked to the edge of the wood running board, which is why tank cars usually did not have route card boards as such, until the advent of metal running boards. For more about route cards, you might wish to read my discussion of the use and application of them at: http://modelingthesp.blogspot.com/2011/11/chalk-marks-and-route-cards.html .
A detail seen in a number of prototype photos is a strip of rust alongside the tank hold-down bands. This occurs because the tank is anchored to the underframe only at the car center, and thus expands and contracts with changing temperature by sliding longitudinally on the underframe. In a prior post about modeling a tank car (that post is available at the following link: http://modelingthesp.blogspot.com/2014/04/associated-oil-tank-cars-modeling.html ), I showed this rust detail. Here is a repeat of a photo from that post; the model is a modified InterMountain kit.
A more challenging task in many cases is lightly weathering a tank car, especially with a light-colored model. This Atlas tank car model, lettered for Warren Petroleum, would be a pretty new car on my 1953 layout and thus is only weathered a bit. Again, I tried to capture the downward streaking on the tank, as well as dirtying up the “glossy new” look of the ready-to-run model.
This then is a general summary of my approach to the separate problems of tank cars, compared to house and other cars such as open-top cars. I will return to the latter in a future post.