How To Acid Etch Concrete

Please refer to manufacturer Safety Data Sheets (SDS) and Technical Data Sheets (TDS) before using any concrete etching acid for detailed explanations of how to safely use.

It’s always recommended to wear the appropriate Personal Protective Equipment (PPE) when acid etching. PPE such as safety glasses, gloves, and respirators are recommended as needed. If you have questions about appropriate PPE for your project do not hesitate to call us.

Proper concrete etching is a REQUIREMENT for all SANI-TRED floor installations on the original surface. Acid etch procedure MUST be followed exactly as specified below for proper installation. Sand blasting, captive ball blast or scarifying the concrete floor surface is always preferable to acid etching when ever possible.

CONDENSED Acid Etching Explanation:

  • Make sure the substrate is clean and free of any previous applied products and other bond breaking contaminants, sealers, etc…
  • Reduce Muriatic Acid (same as hydrochloric acid) with water to a 10% solution. Apply the acid etching solution over the concrete and agitate using a push broom until foaming action stops. (Follow manufacturer's instructions)
  • Rinse with warm water (ideally) or with a pressure washer
  • Mix Apply a “neutralizing solution” over the concrete
  • Rinse with water

DETAILED Acid Etching Instructions

The purpose for acid etching is to remove “latencies” from the surface of concrete floors. When a floor slab is poured, contractors etc often float or trowel the surface smooth by working up a smooth weak film over the concrete surface, this weak film is called “latencies”.


Never acid etch concrete walls, unless the concrete was troweled by hand. Acid etched concrete floors will provide an approved surface in which to produce a penetrating and permanent bond for the Sani-Tred products. While this treatment is effective on new concrete, it may not be completely effective on old concrete with oil, grease, fats, or other bond-breakers present, unless it is properly prepared.

Before any floor coating is applied to concrete, remove ANY previous applied products, sealers, contaminants, bond breakers, etc... The concrete should always be prepared properly in order to allow a penetrating and permanent bond of the SANI-TRED waterproofing products. The bond, durability, and service life of any floor surface material relies on proper concrete surface preparation. Previously applied paints or coatings may usually be removed using our “Off The Wall Coating Remover” which is available from SANI-TRED, then washed and acid etched. Check out this concrete etching tool today!

Mixing and Applying Acid Etching Mixture:

Muriatic (Hydrochloric) acid is normally available from local hardware stores, lumber companies, swimming pool supply, chemical companies, etc… at a 31% to 37% concentration that MUST be diluted with additional water to bring it to a 10% solution. If the “acid etch mixture” is not properly mixed at a 10% solution, the solution will be to weak to properly remove concrete latencies or it may be too strong and etch the surface deeper than necessary, and soak into the concrete surface and contaminate it with a destructive, lingering, acidity after floor materials are applied. Never use "straight acid" mixtures for this reason. Muratic Acid is typically packaged at a 30% dilution (be sure); you want to dilute it down to a 10% dilution (1 part acid to 2 parts water).

The acid etching solution can be poured out, distributed using a squeegee, and agitated the surface using a push broom. Keep the acid etch solution on until it stops foaming. When the acid etch solution stops foaming you can begin rinsing. If the acid mixture does not "foam" evenly over the entire surface of concrete on which it is applied or simply "beads up" on the surface, then this is a sign that a foreign "bond breaker" is on the surface of the concrete. This could be concrete curing sealers, oils, grease, fats, silicone, paints, clear coats etc… If acid alone is used on a concrete surface with a bond breaker present, it will not acid etch the floor, will not remove oils, and will not remove coatings, sealers, etc… because acid is not a degreaser or a remover. Oils may only be temporarily "floated" above the surface, only to be re-deposited elsewhere when the floor dries. If the floor has large areas that are contaminated with oil, grease or other bond-breakers, they should be removed or decontaminated from the concrete surface. 

Rinsing Acid Etching Solution:

Flush away the acid etching solution with warm water (preferably). One may remove acid etch solution with a shop vac, squeegee, rented water handling equipment, or pressure washer (ideally).

Mixing and Applying Neutralizing Solution:

Before neutralizing, it is best to choose which neutralizing solution would be best for your application. After acid etching and rinsing, the concrete should be neutralized otherwise the concrete will be left and acidic contamination which will inhibit PermaFlex from adhering permanently. One can neutralize with either of the following solutions:

  • 1 cup household baking soda per gallon of water, allow it to stand for at least 15 min., do not allow to dry. After rinsing, you can allow it to dry naturally or torch it dry and immediately begin the Sani-Tred application. Most often the best neutralizing solution to use.

Rinsing Neutralizing Solution:

Flush away the neutralizing solution with water. To do so, one may remove the Neutralizing Solution with a shop vac, squeegee, rented water handling equipment, or pressure washer and rinse the concrete with water.

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