First, some linen acrylic paint was used to highlight the brick mortar in places. After wetting a small spot on the wall with water + a drop of Dawn, some diluted linen paint was daubed on the wall. Just like some YouTube videos illustrated, the water helped the paint spread into the mortar "cracks" and helped keep the wall from being so uniformly colored.
Following this procedure, the whole exterior surface save the windows and doors was "painted". Then some charcoal, brown, off-white, and reddish-yellow chalk was dusted on the walls. The thought was to add deeper color below the six or eight smokestacks/exhausts. Hmm, the thought didn't occur to darken the smokestacks, themselves!!?! Oh, well. To hold the chalk dust in place, the whole assembly was sprayed with matte finish.
Next, Tichy fire escapes with vertical ladders were installed. Before gluing together, the parts were spray-painted with satin black followed by a little Testors rust here and there.
That seemed to work OK. So, with a little CA glue, the fire escapes were installed. With all the handling, one railing from the stairway had to be re-glued along with several windows. A couple of figures dropped off, but will be reapplied when the factory is placed back on the layout.
So, the sheen is certainly gone.
The next thoughts are toward some amount of interior scenery -- maybe install a couple of pictures of looms and spinning frames on a floor or two. Also, the buckling of the walls may get some attention if a good straightening process is discovered. Maybe a centrifugal dust collector here and there. . .
And, what about lighting on a floor or two? Just saw a video about fiber optics. Maybe that could be used. Christmas present list?!