Acid etching is a chemical surface prep method that uses diluted muriatic or phosphoric acid to roughen concrete before coating. Most professional installers now prefer mechanical prep methods over acid etching.
Understanding Acid Etching
Acid etching is a surface preparation method where a diluted acid, typically muriatic acid or phosphoric acid, is applied to concrete and scrubbed in before being rinsed off. The acid reacts with the cement paste at the surface, creating a mildly roughened profile intended to help a coating grip the concrete.
Why Acid Etching Fell Out of Favor
Industry standards bodies like the International Concrete Repair Institute now steer contractors toward mechanical preparation instead of acid etching. Acid etching produces an inconsistent surface profile that depends heavily on acid concentration, dwell time, and how thoroughly it is rinsed. It also cannot remove existing coatings, sealers, or curing compounds the way grinding or shot blasting can, and any acid residue left behind can react with a coating and cause adhesion problems.
Acid Etching vs. Mechanical Prep
Diamond grinding and shot blasting both create a more uniform, controllable concrete surface profile and can be dialed in to match what a specific coating system requires. They also handle contaminated or previously coated concrete that acid cannot touch. For these reasons, most commercial and industrial coating jobs today use mechanical prep, reserving acid etching for small DIY projects on bare, uncoated concrete.
Safety Considerations
Acid etching involves handling a corrosive chemical that produces fumes, requires careful dilution, and generates acidic runoff that needs proper neutralization and disposal. Many municipalities restrict acid runoff into storm drains, which adds another reason professional contractors favor mechanical alternatives.
Also Called
Acid Etch, Muriatic Acid Etch
