Any idea how to achieve the grayish-white hue of most of the engines' faces?

A few years ago, I touched up a few of my trains by painting their running boards white (and, in one case, black). Unfortunately, quite a few engines I applied this modification to got and still have a bit of white-out and black paint on their faces, and I'd like to cover those up with a paint identical to the one used on most of the engines' faces. Does anyone know of a good paint color to use?

[Super]

Hi Walt

Is it just paint spots or the whole face? When you say 'White Out' is that the print correction fluid?

Paint spots (and yes, "white-out" in this case is referring to the print correction fluid)

Do you know of a paint that's a close enough match to the colo(u)r of most engines' faces (sans their eyebrows, eyes, and, in some cases, open mouths)?

[Super]

Are the spots very big? maybe a picture might help.

If you're not too afraid of it, you could try repainting the whole face. You would need to take the face off of the body shell, then wash it with soapy water. A color that I've found seems to match the faces in the TV series (slightly darker than the TOMY faces) is Vallejo Sky Grey. You would need to coat the faces with primer before painting, though. A very fine artist's pen works for the eyebrows.

You most likely didn't protect/remove the shells before painting the running boards, and that must be why the paint got on the faces. As suggested by TM2K1, it might be better to just repaint them entirely. If you can't get a good mixture, I'd suggest alcohol to remove the black and acetone or some other solvent for the correction fluid. Just clean the faces if needed first and make sure not to wipe the features off. Also, you should use masking tape to protect the parts that should still be red, black, etc. and be careful if painting handrails and boiler bands. I learnt that the hard way with engines like my original Edward.

I'd try to remove the spots before repainting, very carefully using a cotton bud and a little diluted solvent. You can re-paint when that's gone wrong!

Looking at my various colour charts of model paints, I'd start off by trying something like FS.x6495, which is about the palest un-tinted grey that's readily available. FS.x6622 is another possibility, but still be prepared to mix in a little white.

For an explanation of Federal Standard paint codes, see HERE. There are loads of other more recent colour conversion charts on modelling websites, but this is a very good place to start, and has stood the test of time well.

... is Vallejo Sky Grey...

That's Vallejo Model Color Acryllic 70.989 Sky Grey, which looks rather too dark to me. Better in the Vallejo range might be 70.993 White Grey.

It's not super dark when it's dry.

I'd suggest alcohol to remove the black and acetone or some other solvent for the correction fluid. Just clean the faces if needed first and make sure not to wipe the detail off.

The alcohol solution was, sure enough, what I did to clean a black stain off the bottom of my Oliver's face. It (more or less) worked!

I'll post a few pictures of some of the modification faults I'd like to fix very soon...