Acid Stained Concrete Flooring

Flooring is normally associated with something you put over the top of concrete to cover it up. Historically, bare concrete is not something considered to be attractive or desirable as a final flooring finish. But with newly developed acid etching, technology concrete flooring as a final floor finish is becoming much more common.

Colored concrete has been around for a long time, but never became very popular. Dye can be added at the concrete mixing plant, or the bare floor can be painted after it cures. But this type of finish generally looks pretty ugly. However, etching and staining concrete flooring goes far beyond colored concrete. The colors and patterns that can be achieved are truly spectacular. Most of the stain and etch colors are earth tones. But the variety of subtle shades in coloration is often as rich and deep as natural marble or granite. Sometimes even a leather or wood look can be achieved with the browns, reds and yellows.

The first step with etched concrete flooring is making sure the bare floor is as smooth and free of defects as possible. Any blemishes, markings, cracks or irregularities will show through in the final floor. Acid staining a concrete floor is a lot like staining wood. The stain penetrates and becomes part of the concrete. It does not just coat the surface. The stain adds to the appearance of the concrete, rather than covering it up. So the original concrete is very important. Staining concrete is almost an art form, so you want to give the person doing the staining as close to a blank canvas as you can.

The next step is for the person doing the artwork to test how the floor will react to the stains and acids he plans to use. Not all concrete is the same. It is almost impossible to precisely predict how it will react. He will have a general idea, but testing on an area that will be under a cupboard or some other out of the way location will give him a much better idea what the final floor will look like. Almost always, the various colors of stain will be put down in an artist pattern of some sort. So the next step is to lay out the pattern on the floor.

Then he applies the stains. Generally he uses a mix of hydrochloric acid, water and metal salts. Different types of metal salts will give different colors. The ratio of acid to water will help determine how deep into the concrete the stain goes. The hydrochloric acid reacts with the calcium hydroxide used in the concrete and slightly etches the surface of the concrete, allowing the metal to penetrate. The metal salts, acid, water and concrete then react chemically, revealing deep and beautiful color variations. The result is deep, mottled and variegated but that is a big part of the rich beauty of acid etched concrete flooring. The patterns and colors are part of the floor and are permanent.

After the pattern is fully developed and dried, the surface needs to be thoroughly cleaned and neutralized. You don’t want the acid left on the surface. As a final step the concrete is sealed with an acrylic or epoxy sealer.

The cost of etched and stained concrete flooring varies widely. It has become an art form, so much of the cost is the time, skill and intricate detail put into it by the concrete etch artist. A lot of work goes into one of these floors. But the final result, if properly done by a talented and trained artist, is every bit as beautiful as a marble floor and will last just about forever.