If you have a plain concrete floor or patio and are tired of the boring humdrum gray look, consider staining. Because concrete is porous and neutral, it’s the perfect blank canvas for colors and textures that can simulate natural stone, marble, wood or even leather.
Look for a product that says it’s a true concrete stain and not just a film, which is similar to paint and won’t last as long. True stains are a mixture of water, hydrochloric acid and acid-soluble metallic salts which penetrate the surface and cause a chemical reaction leading to a permanent color change. Each concrete slab will accept the stain in varying degrees of intensity, creating natural color variations that make each project unique. Stains are generally available in subtle earth tones, such as tans, browns, terra cottas, and soft blue-greens, although a newer line of water- and solvent-based concrete dyes have colors in soft pastels and vivid reds, oranges, yellows and purples. Note that since staining products contain mild acids, always use goggles, a face mask, gloves, long pants and a long-sleeved shirt for your protection.
Preparing the Floor
It’s important to make certain your floor is cleaned and prepared thoroughly prior to staining. If you have new concrete, you can skip to the cleaning portion, but if you have older concrete with a lot of cracks and stains, you should take care of those first. Fill cracks with concrete glue, allow to set, then use anchoring cement in the cracks and allow to dry. Then sand the new concrete down. For stains, try a calcium, lime & rust remover. Next, vacuum the floor thoroughly, then go over the surface with a mild soapy wet rag and a stiff scrubbing brush (a wire brush is too harsh) to clean away surface dirt, grease and adhesives. If the floor still looks stained or patchy, consider renting a floor grinder. Finally, use painters tape and paper or plastic to protect baseboards and lower parts of walls.
Staining the Floor
Shake the stain container well before using, then apply the stain with an acid-resistant rag, mop, roller or sprayer. It helps to divide the concrete into sections and use even strokes that don’t overlap. If you’re using a sprayer, keep the end of the wand about 18 inches from the floor. Coat the surface well, but don’t use so much that it creates puddles, and then allow the floor to dry completely. Repeat the process with 2 to 3 coats, noting that colors will get darker with each coat. You may prefer to apply each new coat in the opposite direction of the previous coat creating subtle crosshatched brush strokes. Or, if you’re using a rag, try circular motions to achieve a more rustic look.
Once you’ve allowed your last coat to dry, you’ll need to neutralize the acid. You can do this by simply mixing baking soda and water and creating a thin spray over the floor, allowing it to dry for 5 minutes. Note that it’s important to keep from stepping on the un-neutralized area as you go, since this could leave foot prints on the floor. Follow with a clean-water rinse and squeegee or wetvac the water away. After the floor is dry, it’s try to apply a sealer. For exterior floors like patios, you should consider a water-based or solvent-based acrylic and for interior floors, you can use a two-part epoxy or urethane sealer. In either case, make sure you use a sealer that is meant to work with your brand of concrete stain. If you're worried about slick surfaces, add an anti-slip product to the sealer first, then apply the sealer in two coats, allowing 6 to 8 hours of drying time between each. If you want an additional level of protection for the concrete, you can add 3 to 4 coats of a floor finish wax.