Staining concrete can be an inexpensive way to update the exterior look of your home. Acid stain can be one of the cheapest things you can do and it provides a great bang for your buck. This look is achieved by creating a chemical reaction that alters the color of concrete. Concrete acid stain contains a mixture of water, mineral salts, and muriatic acid. The finished stain will create natural tones that are an impressive improvement from unstained concrete slabs and walkways.