How to Paint Faux Flagstone on Concrete

Clean the concrete with an emulsifying cleaner designed to remove grease and oil from concrete. Mix the cleaner according to the package instructions and scrub the driveway with it using a bristle brush or long-handled broom. Rinse with a garden hose when finished and wait until it dries before proceeding.

Etch smooth concrete with a 10 percent muriatic acid solution. Wear protective gloves and eye goggles as you work. Apply with a bristle brush. Allow the acid to sit according to package instructions, which is typically five to 10 minutes. Rinse thoroughly and leave it for 24 hours so it completely dries.

Roll a concrete primer onto the surface using a long-handled sponge roller. Pour the primer into a paint tray, dip the roller in and roll it across the surface using overlapping strokes. Start at the end furthest from your exit point so you don't paint yourself into a corner. Allow the primer to cure for at least 45 minutes.

Cut large piece of dense foam, such as upholstery foam, into large pieces. You'll need at least three sizes. These are used to stamp the paint into a flagstone pattern on the concrete. Make the largest piece at least 10 inches wide and the smallest 2 inches.

Stir water-based enamel paint that is designed for concrete or patios. Lay a plastic sheet on part of the concrete and a pour a large pool of each color on the sheet. Choose three colors that are in the same color spectrum. For example, choose a dark brick color, then a medium version of the brick and a light whitish brick color. You can also use other color variations such as burgundy or brown.

Mix the edges of each puddle with the neighboring edges so the colors start to blend. You want to still have three distinct colors with the colors blending in the middle.

Soak the largest piece of foam in the paint, dab off any excess paint on newspaper and press it down onto the concrete in the furthest corner from your exit point. Continue dabbing the sponges in paint and pressing it on the concrete. Varying the sizes of the concrete that you use and the colors. Leave a 3/4-inch space between each sponge mark, this represents the grout line.

Fill in any unpainted spots along the edges or in the corners using a foam paintbrush.

Allow the paint to cure according to the manufacturer's instructions before using the concrete.