It's been a while since we visited the thread. Here's a tip from Walther's that basically explains "dry brushing" and the method I used for the Shacks.
Modeling Tips & Tricks
A Dry Brushing Primer
Dry brushing is basically a form of weathering which allows you to add that tiny bit of extra realism to buildings or rail equipment, simulating the effects of Ol' Mother Nature.
Joints, seams and rivets of structures and rolling stock, or anywhere else moisture plays a large part in corrosion, are ideal areas on any model for adding a bit of rust or weathering. Dry brushing is also ideal for highlighting raised details on figures (i.e. a fold in a figure’s shirt) or salt residue on roads or reefer cars.
The process is easy. First, choose a lighter shade of the base color for contrast, for example, pink for a bright red surface. Dip your brush into the contrasting color and wipe most of the paint off on the rim of the paint jar. Then paint a scrap piece of material until there is very little paint coming off the brush. Take the brush and lightly go across the area you want to highlight, building up multiple layers of color. Continue the process until the highlight has visible contrast against the base color.
For rust or oil effects, use rust or thinned dark gray paints instead of a similar color. For any dry brushing effects, remember that you want to build up very small amounts of paint to simulate a dusty or filmy look without completely covering the base color.
The only thing I would add to this is that you can use white to highlight any color. It's like adding sunlight to anything. You should always do this AFTER the ink/alcohol dulling wash. A little goes a long way too.
