I try be a reliable source of information on this Forum, using precise terminology and avoiding shooting from the hip, but I must take my foot out of my mouth over a hasty reply.
I previously replied to a post about the color of the smokebox front on Santa Fe 4-8-4's that a few were painted black, right at the end. However, I subsequently consulted the preeminent living authority on that subject and he assures me that none of the 4-8-4's ever received a black smokebox front while in service.
A few of almost every other class still active in 1951-57 did, but not the 4-8-4's.
It was just money. An engine being painted that was going into storage but would be used again later often received black on the smokebox front, because the painter could just keep spraying and it only took a few minutes. The intention was to graphite the smokebox front later, when the engine was being prepared to be put back into service. Sometimes that never was done, because the graphite had to be mixed and applied with a brush, and was labor intensive, adding expense to a marginally productive engine that would never again work year-round.
The graphite coating did not wash up well, and often was dirty enough to look black, especially in photographs. Santa Fe kept its passenger steam engines pretty clean right to the end, but began to slack off on washing the freight steam as its service time neared an end.
I apologize for the misinformation. Hope nobody sprayed black paint on the front of their 4-8-4 because of it.
Tom