Re: Caboose roofs

I suspect that the "silver" you see on the roof is actually a coating of gooped roofing material that happens to be a light color, not unlike roofing material one might apply to mobile homes today.
Painting the roofing material might or might not last long as the tar and other chemicals would probably over time more resemble a black color.
In any event, silver roofing material on cabooses is not often seen in that period, and was probably whatever they could get their hands on fast and cheap at the time.
I'd vote for a black roof, Grimy Black, but remember rule #1, it's YOUR railroad!