Custom color chalkboard paint recipe 1. Pour 1 cup of paint into a container. Add 2 tablespoons of unsanded tile grout. Mix with a paint stirrer, carefully breaking up clumps. 2. Apply paint with a roller or a sponge paintbrush to a primed or painted surface. Work in small sections, going over the same spot several times to ensure full, even coverage. Let dry. 3. Smooth area with 150-grit sandpaper, and wipe off dust. 4. To condition: Rub the side of a piece of chalk over entire surface. Wipe away residue with a barely damp sponge.