After having bought this structure at a train show many years ago I finally got around to weathering it.
Without any weathering, but lots of dust.
The bricks have been painted with a thin wash of very light grey. The closed in arched door was painted a different shade of red to highlight the difference and it's man door was painted to match all the other doors.
Smoke marks were added over the engine doors. The lights on the maintenance shed were painted green and the roof was rusted down.
Finished Building back on the layout, after a application of Hunter Line black weathering mix. After that dried the roof was dusted with a rust coloured powder.