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How to Acid Stain Concrete

Kalpana Kumari May 4, 2019
Concrete that has been acid stained can give a unique look to floors, patios, and countertops. The same acid stain produces different colors on different concrete. Here's how to do it.
Acid stained concrete is one of the most classic and fashionable ways to do up your house. It is adopted by hoteliers, restaurateurs, and even businessmen to achieve a stylish and outstanding look to their workplace.
There are three stages to acid stain concrete. But before that, it would be beneficial to know how acid staining works, so that you can apply your creativity to bring your desired concrete color into reality.

How Acid Staining Works

An acid stain is a mixture of mineral salts and acid in water. It does not act as an overcoat, but it recolors the concrete. On applying to concrete, the acid and the concrete undergo a chemical reaction. The reaction results in a kind of forced rusting of the concrete.
As a result, the color of the cement changes, which can be subjected to highlighting with the right sealers. This makes the concrete shiny and pleasant to look at.

Acid Staining Concrete

In order to acid stain concrete, you need to spend time, put in effort, and use your creativity. The method to acid stain concrete is standard, but creativity is the key to success. Now you clearly know the working strategy of acid stain. Search well, and then decide which acid stain would give you that wonderful and fabulous look on the concrete.

Prepare the Surface

Clean the surface well, to get it free from debris, grease, and dirt. You might find it difficult and tedious if the surface is old. Ensure thorough cleaning, as the acid stain acts only on the cement portion of the concrete. It cannot stain rocks, sand, and adhesives of tiles and carpet. These adhesives can be removed by scrubbing with adhesive removers. 
Staining such distressed surfaces with acid would result in variegated tones and colors. You may find the color difference from area to area quite unattractive, but there is no need to worry. An overlay resurfacing can give you the desired even finish. 
As every piece of concrete is different, you must conduct a patch test of the acid stain on the concrete. It is advisable to perform the patch test in corners or on an area under a piece of furniture. This way, you can prevent spoiling the look of the concrete surface. 
Once you have decided the acid stain that would give the desired look on concrete, proceed with the next step of applying the acid stain.

Stain the Surface

There are numerous ways of applying acid stain on concrete. You can spray, mop, brush, or rub it on the surface. Generally, professionals prefer spraying. Spraying is easier and gives an excellent look to the concrete. Use an all-plastic pump sprayer. Avoid using metal sprayers as the acid would erode the metal completely.
Brush the concrete in even circular motions with an acid brush. When the acid residues dry, spray the acid for a second time. This is done to eliminate any brush strokes in the first coat. You can skip brushing the concrete if you wish to get a more diffused look. Want a more intense color? Leave the acid for a longer period of time.
Otherwise, neutralize the acid soon. Neutralization is done by adding water, ammonia, or baking powder. Dregs of alkali and minerals will form on the concrete. This is a part of the reaction.
Different stains take different times to react and color the concrete. The time may range from one to eight hours. Never walk on the wet concrete, at least not before the acid stain has neutralized, or else you may leave your feet impression in the concrete.

Remove the Residue

In order to obtain the best possible acid stain appearance, you must perform the residue removal step properly. Prepare a solution of water and detergent. The ratio is a cup of detergent powder to one gallon of water. Mop the concrete with this solution with the help of a nylon brush. Vacuum the residue while it is wet.
Repeat the process, but this time only with plain water. Even after this second trial, some light residue remains. Apply a clean and damp mop to the concrete to give it the finishing touch.

Seal the Concrete

Use a proper decorative sealer to seal the concrete. You can brush, spray, or roll on the sealer. In case you spray the sealer, leave the concrete for at least 48 hours before letting in foot traffic.
For brushing, use a fine bristle brush to avoid any bristles getting left on the concrete. Get a no-texture short-napper roller to do the job. The method of applying the seal on concrete by rolling it on is the easiest of all, but you need to be careful as it also gives the most unpredictable results.
By following all the mentioned steps correctly and carefully, you would be able to acid stain concrete. Acid stained concrete requires less maintenance, and is a thing to be cherished for a long period of time. Enjoy it, and be ready to handle the praise and appreciation it's bound to bring.