Acid Stain Vs. Waterbased Stain

Acid Stains

• Acid stains typically contain water, inorganic metallic salts and hydrochloric acid. When applied to concrete surfaces, the hydrochloric acid reacts with hydrated lime present in concrete, which results in a light etching of the surface. This etching allows the salts to penetrate the concrete surface and permanently color it. After this reaction, the acid is neutralized and the color becomes part of the concrete.

Water-Based Stains

• Water-based stains also penetrate for a permanent finish but do not contain acid or use a reaction to stain the concrete. In addition to water, these stains are usually a mixture of pigments and acrylic polymers. Water-based stains work like a dye, becoming a permanent part of the concrete by penetrating the surface and depositing pigment particles into the pores.

Finish

• Acid stains are similar to wood stains in that they maintain a translucent finish and produce a varied color depending on the condition and color of the concrete. The finished appearance shows a natural variation of color that resembles marble and each finish is unique. Acid stains are typically available in earth tones such as brown, pale blue-green and terracotta. Water-based stains offer a wider range of colors, with finishes that range from translucent to solid or opaque. While the finish color may vary, it is more predicable than acid stains. Standard hues such as black or white are available with water-based stains, and some manufacturers also offer metallic tints to these colors.

Differences

• Because acid and water-based stains both penetrate into the concrete surface, they become permanently embedded and won’t fade, chip or peel. There are a few differences in the durability of an acid or a water-based stain. Acid stains provide a finish that is distinct and unlikely to be duplicated on another concrete surface, but water-based stains are safer to use. They are low in volatile organic compounds and contain no acid or solvents. Water-based stains can also be mixed to achieve a particular color, while acid stains cannot. Water-based stains tend to be more opaque, so the finish isn’t as natural as with acids. Acid stains must also be neutralized to stop the chemical reaction and remove acid residue, which adds an extra step to the process.