How to Change the Color of Flagstone

A flagstone patio or walk is an asset for outdoor living. Though rain, sun, and age may eventually soften and fade the color, you can revive it with a flagstone stain. Cleaning, sealing, adding a stone enhancer, staining, or painting are all options that can intensify or add additional color to your flagstone hardscape.

Before applying any sealer, stain, or paint, clean the flagstones thoroughly. Put on closed-toe shoes, gloves, safety goggles, and a mask or respirator and then sweep the area to remove loose dirt and debris. Mix 1 or 2 tablespoons of dishwashing liquid with water in a bucket and scrub the flagstones. Rinse and allow the flagstones to dry completely.

Stains on the flagstones can be removed with one of the following products: washing soda, vinegar, ammonia, or bleach. Do not mix these products with each other; select only one and mix it with an equal part of water in a spray bottle. Shake well, spray the stains, allow it to work for at least 15 minutes, and then scrub and rinse with a garden hose. Avoid power washing, as the intense stream of water may damage the flagstones.

At this point, evaluate if the flagstone needs additional cleaning with muriatic acid. Carefully mix 1 quart of muriatic acid into 2 gallons of water in a large bucket. Use a stiff-bristled push broom and/or a scrub brush to distribute and scrub the solution into the flagstones. Rinse thoroughly and allow the flagstones to dry for at least 24 hours.

To retain the natural appearance of the flagstones, select a flat- or matte-finish, water- or solvent-based clear penetrating sealer. Apply the sealer according to the manufacturer's directions, generally by spreading it over the stones with a sponge, paintbrush, roller, or sprayer. Wait five minutes and then remove the excess sealer with a clean rag. Allow at least 30 minutes between applications and then allow it to dry and cure for 12 to 24 hours according to the directions on the label.

If you prefer a darker "wet" look, apply an enhancing sealer to the flagstones. Apply an even coat of the sealer to the flagstones one by one and then remove excess product immediately with a clean rag. Allow it to dry for the recommended time before applying additional coats to further darken the flagstones.

No matter which sealer you choose, do not allow anyone to walk on the flagstones until the product has completely cured. After it is fully dry and cured, test it by pouring water on the stones; if the water beads, the sealer is doing its job.

Apply a semitransparent concrete stain or paint to change the appearance of your flagstones without making them into a monolithic block of one color. Use a pump sprayer or other method as recommended on the label to apply a fine spray onto the cleaned flagstones. Feather the edges of the stained areas as you work to enhance the natural stone look.

If multiple colors are desired, use multiple semitransparent stains, blending carefully around the edges. Alternatively, use two or more standard concrete stains combined with an equal part of water or solvent to thin the stains and make them translucent. Spray each color separately; apply one and then quickly spray the adjacent color and lightly blend the edges.

After the stain has dried, apply a second coat if desired to intensify the colors. When fully cured, seal with a clear or stone-enhancing sealer to protect the flagstones.

When flagstones are damaged and replacement is not an option, consider repairing and then painting the flagstones to protect them from further damage. A painted flagstone floor or fireplace might combine several colors in a subtle sponge-painted technique, or you can simply roll the paint over the flagstones for a continuous color statement.

Prime the flagstones with a masonry bonding primer first. Allow it to dry and then apply several coats of latex paint over the patio or floor to ensure full coverage. In general, painted flagstone may also require several coats of a polyurethane sealer to increase the durability of the surface.