Smokebox grey/graphite color

While I can't recommend a paint color, I can add that the graphite/linseed oil mixture used on many real locomotives varies depending on the mixture and also changes shades as it is baked on the metal from the heat of the fire.

There are all sorts of acrylics on the market that may be applied with a brush, leaving NO brush marks (use a decent - not fancy -brush). I've done it many times. I painted all

the silver (not the "stainless") on a Lionel Empire State Hudson, drivers and all, to a gray to reflect its later service colors. Excellent finish (I've posted photos here, some time back). I used Model Color paint by Vallejo, from Hobby Lobby. They offer "steel" colors, and the like. Some might do. Check their website, of course.

I applied the paint straight from the small bottle - 1 coat did it. Next day I touched up the bits I missed. Blended in completely. May be thinned, of course.

$3.29/17 ml. bottle; way less than the cost of the loco.  

Stopped by Micheal's today and found they carried a good variety of Testors paints...both bottled and spray can.  Coincidentally, I purchased a spray can of their flat Graphite Grey for the same purpose.

Bruce

Check out Weaver scale cost paints one one for metal one for plastic

 not available in bottle or spray can

http://www.weavermodels.com/