Weathering/painting the underside of rolling stock kits

I’m just starting to build some rolling stock kits and realized I don’t know good ways to paint or weather the undersides–spray it grimy black or ??? I’d appreciate any advice.

Thanks,
Mark

Grimy Black is a good starting point for your underside–since most folks won’t see your undercarriages, that might be all you need to do. On older rolling stock you might want to add some rust, and a few spatters of dirt to match whatever terrain your railroad runs through (a dusty color for a desert/southwest line, darker brown for farmland, sooty gray for urban railroads) can tie your rolling stock to the land it runs through. Passenger equipment, of course, will be a lot cleaner.

I use a really snappy shade of flat brown from Polly Scale (water base) called DIRT. If you have an airbrush, I have found this a fast, easy and realistic way give the underside that brownish color all railroad cars seem to aquire. You can vary the shade between cars if you want by adding various small amounts of grimy black. the trucks, including wheels eventually end up in various shades of this color too.

In fact , if you can adjust your airbrush fine enough, you don’t need to mask the sides of the car, and the little bit of overspray that gets on the sides adds to the weathering effect nicely. Practice on a dispensable car first. Dan

JetRock and Sparkingbolt have excellent suggestions.

Just a little more info: In north Florida and especially Georgia locomotives pickup quite a bit of the “red-orange” clay during rain storms so I mix a combo of rust & light brown for the effect on loco & freight car trucks and the lower 1/4 of the body. Just a very light overspray on some of my Seaboard Coast Line rolling stock. No need for masking.
Take a paint brush and apply “thinned” rust on the outside of your knuckle couplers. Hope this helps!

I try weather my cars depending on how “old” they are and what they do. For the undersides I usually hit the brake details and truck sideframes with some rust…if its a “new car” I make it a brighter rust and an older one I’ll mix in some darker brown. I do it with a brush and am not too careful if it gets on other part of the frame. Sometimes on the newer cars I’ll go back an put small irregular areas on black to look like the remaining paint on the items. After I do any other weathering to the car…rust streaks from the roof sill or graffitti decals, I hit it with the airbrush and do a wash of thinned our grimy black and some drops from the paint brush cleaning jar. I start with the underside and spray a good bit on the frame and trucks, then I weather the body. Like Antonio said, think of the cars origin when selecting colors…northest will have alot of grime from rain and snow wet spray, the south muddy and the west dusty.

I have found that nothing seems to irritate my wife more than seeing me “dirty” up that perfectly good new boxcar i just bought. [:)]

I paint my underframes grimy black, then drybush on various rust colors.

My method is pretty simple. I like roof brown for the color as it simulates the grime and rusty powder that comes from the track and wheels. I brush paint and don’t have an airbrush. I also add rust to metal parts, such as the truck springs, trucks, brake equipment etc. I use metal wheels and paint the wheels the same roof brown.

I know that the bottoms of the cars arn’t seen but I enjoy painting them anyways.