I let the base dry thoroughly and then coated both the depot and the base with a coat of Testor's Dullcoat. This will seal in the weathering and give it a flat finish all around.
This is wet, so its a bit shiny. I'll take a picture tomorrow when it has dried. All that is left to do is to add signs and people, baggage, and the scenery details. Oh, and the very last thing is glass.