=>I'm scratchbuilding a water tank and just got stuck: what color were the =>hoops on the tank? Were they painted black or were they just rust colored?
When new, some were painted black, others were painted the same colour as the tank. Eventually, they rusted. But just how rusty they got depended on the rialroad's maintenance policies. I'm afraid you'll have to check the specific prototype you're modelling. The most likely colour is the tank's colour, with some rust. Most of the photo's I've got show the bands as being the same colour as the tank.
HTH
Wolf Kirchmeir ................................. If you didn't want to go to Chicago, why did you get on this train? (Garrison Keillor)