Turquoise Blocks with a Red Thread

Paint on an old block wall usually fails from behind. Damp moving through the masonry carries salts with it. When the water dries out under the paint, the salts form crystals that lift it off in flakes. Patches of bare gray block show through several shades of turquoise here, crossed by one thin red cord. That single line of red does a lot of work in a turquoise wall jigsaw puzzle that is otherwise all blue-green.