As model railroaders, many of us are trying to duplicate the real world in miniature. The ready-to-run rolling stock that we purchase at the hobby shop is better than ever, but then it's up to the modeler to make it really look real. We have to have a firm understanding of what kind of weathering occurs to freight cars, both what it looks like and how it occurs, to know what we need to add to a car to make it look less like it's straight out of the paint shop. Let's take a closer look at one specific covered hopper car that I found today to see what we need to duplicate on our models.
First, a disclaimer that really isn't a disclaimer... There really isn't anything special about this car, it's just the first car that I saw on the tracks today. The location isn't anything special either, it's at a local grain facility that happened to be across the street from the model train show I attended today. I didn't go searching for any specific type of car, or any specific attributes in a freight car, I just looked at what was out there.
So, what do we notice about this car? The first thing that I notice is the lack of graffiti anywhere on this car. There are so many cars rolling out there with such huge pieces all over their sides, it's refreshing to see one that hasn't been touched yet. Getting over that, the next thing I notice is how prominent the seams are on the side of the car. We know from looking at other similar cars, that these seams are often where rust begins and flows, so it's natural that dirt would collect there. But what are all those speckles on the car side?
Those speckles are all little scrape marks from rocks that have been kicked up along the mainline. That's ballast that has repeatedly hit the side of the car. It's just like when a rock is kicked up into your windshield on the highway by a car in front of you; those little pebbles on the highway leave dings in your windshield, and they leave dings in the covered hopper too. This closeup photo shows something else that is the result of debris kicked up by the car's wheels, too. See that dark horizontal line near the bottom of the hopper bay?
That's mud, grease and grime that has flown off the spinning wheel on the truck right next to the hopper bay. You should notice here that this grime line is very straight, and is generally directly above and parallel to the rail's location below the car. This kind of weathering should be familiar to anyone who has tried bicycling in or immediately after a rainfall. On many college campuses across the US, this phenomenon is known as "freshman stripe," and we can see the same weathering feature on the ends of the car.
Looking at just one of the stripes on the end of the car, we see that it is, like the stripe on the hopper bay, directly above and parallel to the rail below the car. On this car, it is here where we see the first hints of rust on the car itself. We can see the rust beginning at the ladder joint directly at the top of the stripe and the rusty water trail flowing straight downward on the car from there. We can also see that the stripe covers part of the air brake cylinder, and that relatively clean spot directly behind the cylinder tells us the angle from which the grime was thrown onto the car. The stripe was made by the wheels that are closest to the car ends. If we looked underneath box cars, we would see the same kind of stripes, and we can actually see these stripes on the boxcar ends too, but those are made from grime flying off the wheels of adjacent cars. With that knowledge, we can conclude that the stripe we see on this car was also partly formed from grime flying off the wheels of adjacent cars. The presence of grime on the vertical member of the ladder directly in front of the stripe shows us that this car has received weathering from adjacent cars in the same way. And, if you take a closer look at the angle shot that leads this article, you can see that there are in fact two stripes on the car end. The other end of the car has the same kind of stripes from the wheels at that end of the car. There is one other important item of weathering that we need to look at on this car, but to see it, we need to either climb the car's ladder (which I don't recommend for anyone who does not need to be there; and as railfans, we don't need to climb up there) or step back a little way from the car side.
See that patch of yellow just under the roofwalk just to the left of the middle of the car? That's corn. Yup, corn. Specifically, it is corn that has spilled next to the car's roof hatch when it was being loaded some time in the past. Sometimes, when grain is spilled on the car roof like this, some of the grain will actually germinate and grow, so it is possible to see covered hoppers with fully grown corn stalks standing up on their roofs. The grain that is spilled there is wetted by rain during the car's travels, which, when combined with the heat from the sun, can help to glue the grain to the roof and help to feed the plant growth (Don't believe me? Haven't you ever grown a Chia Pet?). Just as grain can be spilled on the car roof next to the loading hatches, grain can also spill out the hopper bottoms, next to the unloading hatches. But, the grain that spills out the bottom, lands on the track and finds its ultimate home between the rails.
So not only does the car itself receive weathering that can be duplicated on a model, the car can cause weathering on the track that can also be modeled. So, the next question is how do we model the weathering that we see here? Briefly, we can use a thin black or dark grey pen to simulate the seam lines on the side of the car. The flecked off paint from rock damage can be simulated by stippling a very coarse dry brush along the lower half of the car. The grime line on the hopper bay and the freshman stripe on the ends can be simulated with a fine spray pattern on an airbrush with grimy colors. The spilled grain (both on the car and between the rails) can be simulated with very finely ground foam. What? You want specific cookbook-style steps to model each of these weathering patterns? That will have to wait for another article...