How to Acid Stain Concrete

Tips for a successful acid stain application:

There is nothing more encouraging than coming across a beautiful, naturally colored, mottled and variegated acid stained concrete floor that has stood the test of time. With acid staining becoming the standard when choosing a way to color and finish a concrete slab, we might ask ourselves: How can we ensure a successful installation with such an unpredictable product?


ACID STAIN DISCLAIMER: Acid stain coloration systems create translucent color effects and are not designed to hide surface discoloration, blemishes, impressions, cracks, markings or other construction variables.

Although the advice we are about to give seems straight forward, it is following the directions and being diligent that is the tough part.

First: Adding translucent color to anything (translucent being semi transparent) the pattern and colors of the substrate will show through. Similar to applying a wood stain to a piece of wood with knots and wood grain. The pattern of the wood will still be apparent and desired after the stain application.

Concrete stain is similar to wood stain, but can actually highlight and intensify the variations found in the concrete. This includes natural as well as man-made blemishes and markings. So the first step to getting stain correct is to make sure the canvas on which the stain will be applied is clean, free from unwanted defects, stains and markings, so that it can be ready for coloration.

Second: Color charts provided by manufacturers are meant as a guide only. Because acid stains react differently to each type of surface to which they are applied, it is imperative that a sample is done on the actual concrete that is going to receive the treatment. 

The methods and timing of the sample installed should coincide with how the rest of the surface will ultimately be installed. Even though additional variables may be encountered during the application, doing an onsite sample is the best way of predetermining how the stain will react with a specific substrate.

Third: Applying acid stain is as much functional as it is art. When applying acid stain, it is necessary to understand the technique as well as how much to apply. Every now and then, potentially great jobs turn into disasters because of improper application methods. Too little product won’t give complete coverage, nor will it etch the surface sufficiently to deeply deposit the color. On the other hand, too much product can cause unwanted puddling and over-react the areas where it has pooled on the surface.

Then there is the scrubbing method. If scrubbing isn’t done with a natural flow and pattern, mop lines and obvious swirls may appear.

If all concrete surfaces were the same, then an exact application procedure could be developed, but this simply isn’t the case. It is with experience that technique is developed, and this is why the skill level of the installer plays an important role when choosing an acid stain finish.

Fourth: Removal of the residue and neutralization of the surface is of key importance to the success of and acid stained concrete finish. Residue from the concrete acid etching that took place must be removed and the surface should be neutralized to ensure proper adhesion of the sealant or coating system

The surface is still subject to staining and damage at this point and care should be taken to thoroughly wet and neutralize the entire area to avoid boot prints, splashed residue marks and other man-made blemishes.

Fifth: Once the concrete is sufficiently dry, a sealant of coating should be applied. This is usually the last stage of installation but must be done correctly, as an improperly applied sealer system can show roller lines, leave lint and debris in the finish, or delaminate or flake off the surface if it is installed improperly. Experienced professionals have ways of choosing and applying the right sealer for the job. Application techniques include spraying, cross hatch rolling, back rolling, and buffing in the case of a wax finish.

It is now easy to understand that there is a lot of work that goes into a stained concrete finish. But like anything else, practice makes perfect. So when its time to hire a professional to do the work make sure you choose someone who has the skills and abilities that match the level of difficulty of the job at hand. Go and visit past work and talk to some of the owners of the floors.

the next piece of information is CRITICAL:

Even if you hire the best acid stain concrete contractor in your area, their abilities will depend on the surface on which you give them to work with. It may not be possible to completely hide and blend-in the color with a badly stained and damaged concrete slab. The concrete slab is the decorative concrete artist’s canvas, so it MUST be kept clean and free from stains, spills, paint and other markings.This will ensure that the finish will be everything you hoped for and expected when you chose to use acid stain as a concrete finish.

See images of this project: Acid Stain Concrete Restaurant Floor