Acid etching is the process of applying an acid solution to your concrete surface, which allows the acid to react with and, for effect, “etch” the concrete. Using this process for your concrete will definitely remove most surface deposits and other unnecessary elements on it. Acid etching is commonly used for commercial concrete surface preparation.
Another method of preparing the concrete surface is shot blasting. But this one requires special equipment and trained professionals (or even special contractors for concrete). Acid etching is the most practical method that’s available for the do-it-yourself homeowner.
Guidelines for Acid Etching
Concrete acid etching will not be able to remove previous sealers or the concrete surface itself. These must be removed manually or mechanically by shotblasting, sandblasting or scarifying. However, sealers that have soaked way in too deep in the concrete may not be removed at all.
Acid etching is most commonly used for the surface preparation of home shops, garages, basements and general concrete.
If the concrete surface is dirtied with oils or grease, cleaning the surface with an alkali detergent cleaner is essential for a proper clean. You can also use a detergent partnered with a steam cleaner as another option.
Acid Etching Agents
- Hydrochloric Acid – Sold in 31% solutions. These must be diluted to 10 – 15 %. For every 40 – 50 square feet, one (1) gallon of agent must be used. Remember to take extra precaution and care when applying or using this as it has very strong fumes. For the best application and safety precaution, we recommend hiring a professional decorative concrete contractor.
- Sulfamic Acid – this consists of a white powder dissolved in hot water. It’s less dangerous to work with compared to the other acids and the best choice for non-professionals. You can use this by mixing one pound of sulfamic acid with 1 gallon of hot water for every 300 square feet of your concrete surface.
- Phosphoric Acid – this acid etching agent produces less fumes and can be used around metals like carbon or galvanized steel (commonly weak when used with acid).