Developed in the 1950s these wagons provided a self-clearing hopper discharge wagon suitable for bulk powder products which required reliable weather protection. Typical loads included salt, soda ash and dry sand, all of which would be lost or damaged by wind and rain, or fail to discharge through the hopper when wet.
Often these wagons would have run in groups on a fixed route, the lettering helped ensure the empty wagons were returned promptly and not reloaded with materials which might cause contamination of the soda ash.