The weathering discussion among the pirates eventually moved to the underside of the cars on our railroads. Too often, guyw will weather the sides & the roofs (even the cars' interiors) but leave the underside of the cars untouched. When you think about it, this is the area that would see the effects of dirt & grime the soonest since dust, dirt, ballast, grease & water are all over the tracks themselves. And, since the cars have no fenders, that collective gunk will ultimately find its way to the bottom of the car and the trucks that hold the wheels.
During our discussions, it was pointed out that the trucks on our rolling stock are especially difficult to weather since most of them are made with Delrin. Delrin is a tough, specially formulated engineering plastic that has kind of a slippery, oily feel to it. While this is great for the rolling characteristics of the car, that slippery surface isn't the easiest to get paint to stick to. Some guys actually have little blasters that will scuff the surface of the plastic enough to allow paint to stick better. Others have found that good, old spray paint from a rattle can will make a good enough base for detailed weathering.
While you are weathering the trucks, don't forget the wheels either! They aren't smooth in the first place so there are lots of places where "stuff" can stick to them. Several manufacturers now make holders for wheels that you can use when spraying them with a coat of rusty or dirty looking paint. Be sure to remove the paint that is on the actual wheel tread; this is the one area that the car's wheels will be nice and shiney. Besides, if you leave it there, it will eventually wear off and accumulate on the wheels of other cars and locomotives. The gunk on the cars will inhibit their free-rolling characteristics and the gunk on the loco wheels will certainly impede the free flow of electricity from the rails to the motor onboard.
One final look at some more car weathering then we can move on to other things.