On coaches with steel roofs I generally see two coatings. Either black or silver.
What are those materials generally?
Often the black looks like it could be tar. But the silver always looks like paint or galvanizing.
What is that stuff? Is there a standard practice in such matters?

In the south, a coating called "Cool Seal" made for trailer roofs is common. It is the silvery stuff that reflects the heat.

dave

In my experience, black roofs can either be paint, or the thicker asphalt coating that the railroads called car cement. I suspect all were painted when new. The advantage of the car cement is it would seal any leaks that had developed around rivets and between plates at lap seams.

The heavy silver coating that Dave mentions is like a silver version of car cement, used for the same leak sealing ability on mobile home roofs. It seems to have been developed in the sixties or very late fifties, and therefore is doubtful many railroads used it on heavyweight cars while they were still in revenue service, but may have used it on cars converted to camp cars.

On our ET&WNC #434 boxcar, there were the remnants of some "Cool Seal" type of product on the roof of the car. There are also some slides taken of ET freight trains in the late 40's which show several cars to have their roofs treated in such a manner.

Matt Bumgarner