Concrete staining is an excellent way to enhance the appearance of your interior or exterior concrete and make it one of a kind. There are two types of concrete stains, acid stains and water-based stains. Both stains can be applied to fresh or longstanding concrete and will never chip, fade or peel away. Acid staining tends to provide a subtler, earth toned palette while water-based stains offer a much larger variety of hues. Acid staining is an application which includes the combination of water, hydrochloric acid and acid-soluble metallic salts that penetrate the surface and have a chemical reaction with the hydrated lime in the concrete. The acid lightly scratches the surface which allows the metallic salts to infiltrate easier. Water-based staining is a mixture of acrylic polymers and pigments that penetrate the concrete to produce a permanent color.
Unfortunately, acid washing does not disguise imperfections in concrete; so, surfaces with extreme cracks or spalling are not ideal candidates for acid washing as any repairs will show through the stain.