Actually, what Dubin said referring to how Pullman Green came about was
this:

(quote) ...The result was a dark olive green originally called Brewster
green and later referred to as Pullman Green--more specifically No.70-10
geen. It wasn't a pretty color. It was utilitarian. It withstood weather
well and it didn't show dirt. (Years later, about 1960, when Canadian
National Railways was revising its image, research revealed that urban dirt
is black and rural dirt is yellow. Urban dirt and rural dirt simply amounted
to more pigment on top of Pullman green, which was a yellowish
black.(unquote).