(First, thanks to all the forum members who responded to my post “Should I get an airbrush?”. You have been a big help.)
I embedded some questions in the aforementioned post on which I still need clarification:
In the Kalmbach booklet on weathering, the illustrations show the user spraying both wheel/truck assemblies and knuckle couplers with paint while weathering. Is this standard operating procedure?
Of course I would never spray a loco this way, but is it not going to seize up the operation of wheels and couplers on rolling stock too [:O] ?
Another question: what is a moisture trap in an airbrush air line and is it a good idea?
I never use an air brush on the couplers and wheels. Instead i use a small paint brush. i usually take the wheel from the axle and very carefully paint the outside of it paying close attention to the axle and making sure i don’t get any paint on it especially the tip. (if i do, I get the paint off right away with thinner.) Paint on the axle will definetly seize up the wheel action.
I then paint the outside of the truck, let it all dry, then re-assemble the wheels into the trucks. Double check that no paint gets on the wheel axle or the inside of the truck bearing housing and check to see if the wheel spins freely when assembled. I usually use a mixture of floquil’s rust and grimey black. The color combination looks about as real as it gets.
As for the couplers, i usually don’t paint them at all, but if i do, i’ll use rust colored chalks. a Kadee coupler spring is very small and i don’t want any paint on it to seize it up.
I don’t get the idea of brush-painting couplers. An airbrush applies a thinner, more even coat of paint that won’t interfere with coupler operation. I’d be much more likely to gum up couplers with a brush than with an airbrush. I also paint all my car wheelsets with my airbrush, in this case mainly to save time. I use fixtures that hold a batch of wheelsets so I can do several at once, with Polly Scale Oily Black on the wheel faces and a mixture of Rust and Roof Brown for the backs of the wheels and the axles. (That’s for my pre-roller-bearing modeling era, because the old journal bearings pumped oil onto the wheels. For modern cars I’d use the rusty mxiture on the wheel faces too.) I protect the needlepoint axle bearings with Walthers Magic Masker before spraying the wheels, and clean the wheel treads to bright metal after reassembling them in the trucks. Good luck, Andy
Aside from a much thinner coat of paint, the advantge of spray painting is doing a bunch at one time. I use a piece of courrogated cardboard, I make a small slit so I can push the back side of the coupler down between the courrogations and hold the coupler upright. I can spray 10 to 20 couplers at one time. That way they are in a box on my workbench ready to install when I need some.
As for trucks, I cut some 1/4" dowel about 4 to 6 in long, sharpened the end in a pencil sharpener and installed in holes drilled in a piece of wood. The truck goes over the dowel point; with a little push and twist, it will stay put; otherwise it will spin. I can paint up to 8 trucks at one time
Chuck Clark has the answer for the trucks & wheels. As to the couplers, I would dry brush them. After dipping the brush in rust color, wipe it on a paper towel 'till just a little paint comes off, then do the outside of the couplers. The facing parts of the coupler would not be rusty, but would be black/silver from use. Dont do all the couplers - an occaisional one would be new - just like don’t weather all your cars heavy - they vary from new to ready for the scrapper’s torch!!![:)]
And if you’re doing passenger car couplers for a road that regularly paints the underframe/trucks/couplers, etc (such as Santa Fe), you can use a Metallic Silver Sharpie. Works quite easily, and the “paint” layer is very thin.