Staining concrete is one of the most popular applications for transforming concrete.
Homeowners, designers and builders are drawn to stained concrete because of the unique outcome that can be achieved combining colors, artwork, sawcutting, application techniques, etc., on cement flooring and other substrates. The results are limited only by creativity.
Because of concrete’s porous qualities and neutral tone, it is the perfect blank canvas for topically applied color. Using acid-based chemical stains and dyes, Pristine Concrete has been able to achieve rich, earth-toned color schemes resembling natural stone, marble, wood, or even leather, giving a completely custom look to cement floors, concrete driveways, patios, walkways, pool decks, concrete walls and more.
Most acid stains are a mixture of water, hydrochloric acid, and acid soluble metallic salts. They work by penetrating the surface and reacting chemically with the hydrated lime (calcium hydroxide) in concrete. The acid in the stain lightly etches the surface, allowing the metallic salts to penetrate more easily. Once the stain reacts, it becomes a permanent part of the concrete and won’t face, chip or peel away. Like stains on wood, acid and solvent-based stains are translucent and the color they produce will vary depending on the color and condition of the concrete that they are applied to. Each concrete slab will accept the stain in varying degrees of intensity and any stains or discoloration will likely show through.
When to stain? Stain manufacturers suggest 14 to 28 days depending on curing of the concrete. With new construction we like to stain after drywall is taped and textured, but before paint and cabinets, due to the water needed to clean the concrete before and after staining. The area to be stained must be closed off to traffic. The dirt and oils on foot traffic will leave undesirable effects. The process will take three to four days, depending on size and design. Protecting the floor after installation is the owner’s and general contractor’s responsibility.
Color Choice is often dictated by personal preference or a desire to match or complement an existing color scheme. The most impressive stained surfaces display multiple hues, sometimes separated by joints or saw cuts, then meticulously hand-applied to create detailed graphic compositions. Regardless of what colors you choose, be aware of the following:
- Wide color variations are normal.
- Surfaces will have a mottled, variegated appearance, and these variations will be emphasized when the final coat of sealer is applied.
- Because the stains are translucent, the discoloration in the concrete due to age, manufacturer, oil spots, paint, etc. will show in the finished floor (character scars).
- Color effects will generally be more intense on new concrete than on older or weathered concrete.
- Pouring a mockup slab on-site when placing concrete will give a more accurate sample of color.
Protection and Maintenance
Since the stain only penetrates approximately 1/32 of an inch in to the concrete matrix, it is only as strong as the surface. In many cases the very surface of the concrete can be weaker than its mass due to finishing techniques and curing methods. Too much water on the surface when brooming is very common and dilutes the cement content and creates dusting and in return, stain failure. Although stain is permanent, the top layer of the concrete surface will eventually wear away as the surface is worn by traffic or weather exposure. To prolong stain life, we recommend keeping stained surfaces protected with multiple coats of sealer (outdoors) and a floor wax (indoors). How much traffic the surface receives often dictates the amount of on-going maintenance required to protect your investment. Maintenance is usually a simple matter of dry dust mopping and occasional wet mopping with a neutral-pH cleaner. Floor wax should be applied to protect the sealer from wear every six months for residential and once a month or more for commercial.
Stained concrete supports GREEN concrete floors and when left exposed, can function both as the foundation slab and finished floor. This eliminates the need for carpeting and other floor coverings that would eventually require replacement. To enhance the appearance of the floor and make it easier to maintain, it can be stained and polished or sealed.
Because of their thermal mass, concrete floors also are key elements in passive solar home designs that use high-thermal-mass materials to collect and store radiant energy. Most homes in California are constructed on a concrete slab, according to the California Energy Commission. In winter, concrete’s thermal mass absorbs heat by direct sunlight through properly oriented windows. At night, the concrete releases the stored heat to warm rooms. Passive solar heating can be supplemented by energy-efficient radiant in-floor heating systems. In the summer, concrete floors shielded from the sun will stay cool longer and can actually help lower air-conditioning costs.