Tonight I used an acrylic wash on the platform’s brickwork to represent mortar. For the wash, I diluted FolkArt Wicker White acrylic paint in water then added a few drops of dish soap to reduce the surface tension. Then I painted several coats over the brick. Most of the acrylic ran into the spaces between bricks, but some remained on the surface, which gives a nice “chalky brick” appearance.
Photos never do the mortar justice–it practically disappears in just about every photo I tried to take, but here goes: