Most steam locomotives, even ones just out of the erecting shop, are seldom all-black, as non-lagged areas, such as the smokebox and firebox are usually treated with a mix of oil and graphite, which can range in colour from brown, to grey, and even silver, depending on the mixture and the preference of the owning railroad.
I prefer to represent most of my steamers as having been in service for sometime, but in most cases, well-maintained.
To that end, cabs and the sides of tenders might be out-of-the-bottle black, but the boiler would be black lightened somewhat with either white or grey…maybe both, as would be the tender deck, while the running gear would be somewhat similar, but with some brown added, and perhaps more grey.
Smokeboxes and fireboxes might be grey-ish, or brown, with a tinge of rust, dependent on when they were last treated with the oil and graphite mix.
Once the painting is done, clear coat is applied, using a fairly glossy version on the cab and tender sides, and a less-shiny version on the boiler jacket. The running gear gets an even duller, but still somewhat shiny, clear coat, while the tender deck get an application of Dullcote.
The smokebox and firebox get no clear coat at all, as they should be dead-flat and not smooth-looking, as would be the case if Dullcote were used.
I also use a brush, and the same semi-gloss as is used on the boiler, to brush-paint the piping and appliances on the smokebox and firebox.
Here are a few examples…
…this one’s pretty-much just out of the shops…


…while this one’s been in service, but still not looking neglected…
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