Paint Touch-Up Help

Hi, I am new to the group. Back in the hobby after building models as a kid, but now want to build more protypical rolling stock. I model the GN (and other Western roads) in 1965.

Question: I have a Front Range UP box car that I want to upgrade some details on, including stirrup steps, grabs, brake wheel and running board. I want to preserve the factory painting and touch up the new details by hand after application.

Does anyone have suggestions or experience to share for matching colors on painted models? I would like to use Modelflex or similar water based colors and brush paint the details to match the rest of the car.

(I reposted this with a changed subject that hopefully helps with responses)
Thanks! Jeff Helm

The best that I can tell you is that often when repairs or modifications are done on a unit they are painted with the closest match on hand. Frequently this is several shades off so however poor your paint match it can be considered prototypical. Good luck.

Just match car to it’s color. ie,boxcar red,etc.or if you have a local hobby shop,take it there and compare to paint rack. The color shouldn’t beto close, unless it’s brand new from factory, so a little weathering will hide color flaws. UP cars built in forties and fifties were boxcar red.