This building has once before fallen beneath my weathering attempts, with little success. I'd tried doing it without powders, using inks and dry brushes only. With it being such a numpty building, I thought it was worth paying another visit to the factory floor. Here's how the inspection went.
This might be too dirty now due to too much use of the black powder, particularly on the light walls. Using the mucky paint ivory and wiping it off the chimney worked well to create the brick mortar. Going to try a card made factory next.