Decorative concrete expert Jason Geiser, of Deco-Crete Supply, acid washes an area of concrete to lighten the color of stain. Acid washing is the process of removing the top layer off a concrete surface to open its pores and provide a clean slate for a coating.
The acid washing of concrete is a requirement after the concrete has cured sufficiently, in order to remove surface efflorescence and to open the pores before sealing. This will help the sealer to penetrate and result in a superior bond between the sealer and the surface.
Acid washing etches the upper layer of cement, exposing more of the sand in the concrete mixture and making the surface feel rougher. Acid washing also removes stubborn stains. Home improvement stores sell several acids for concrete etching: citric, sulfamic, phosphoric or muriatic.
Acid washing is a cleaning process that uses a combination of hydrochloric acid and water to remove stubborn stains and debris.
Acid washed flooring is created by applying a solution of acid, water and inorganic chemicals to a cured concrete surface. Variations in the concrete's porosity, density, and water retention creates the unique marbling effect and extraordinary hues in the finished concrete.
Mix your muriatic acid.
High concentrations of muriatic acid can etch concrete, glass, remove paint, dull chrome, and cause other issues. Below is a summary of how much to add to a gallon of water: Heavy cleaning: 3 ounces of muriatic acid to one gallon of water.
Brush or spray the acid solution on the concrete, wait eight to 10 minutes, then neutralize the acid by spraying the surface with a mixture of one cup of ammonia in one gallon of water. Kill Mold—Use muriatic acid to kill stubborn mold and mildew on hard surfaces, such as brick, tile, concrete, and stone.
Average pool acid wash cost is $202, cost ranges between $178 to $225 for a pool measuring 500 square feet, according to Improvenet.com in the US in 2020. Of course, prices will vary based on location, size of the pool and the time of the year.
How Pool Acid Washing Works. Pool acid washing is a process where chemicals—mainly hydrochloric acid, also known as muriatic acid—are combined with water and are sprayed onto your pool's surface to remove any grime and build-up. A professional pool cleaner will then use a brush to scrub out the staining and other grime ...
Acid Wash the Pool
Pouring acid onto a dry surface can damage the plaster. Pour the acid mixture in a circular pattern, and have the person helping you follow behind with the acid brush and scrub the surface. Let the mixture sit for 30 to 60 seconds, depending on how dirty it is.
The acid works well on concrete and on many masonry projects because it neutralizes alkalinity. The surface becomes “etched” and clean, which allows for the proper adhesion of a new coating. Despite its effectiveness, muriatic acid should be used on concrete stains only if you've tried gentler alternatives to no avail.
Acid Etching
Next, spray the acid on the concrete surface and scrub vigorously. Then, neutralize the acid and wash the concrete surface. The acid etching will completely remove the old sealer from the concrete surface and you will have a fresh surface ready for reapplication of the sealer.
Phosphoric acid is a good substitute for muriatic acid and in most situations will clean surfaces just as well with less risk. Phosphoric acid is a main ingredient in many commercial grout and concrete cleaners that are readily available to consumers.
Muriatic acid is one of the names for hydrochloric acid, a corrosive strong acid. It is also known as spirits of salt or acidum salis. "Muriatic" means "pertaining to brine or salt". The chemical formula for muriatic acid is HCl.
Your pool generally only needs an acid-washing every five to seven years if you regularly treat and maintain the water in it. Acid-washing your pool more often can damage the plaster coating inside the pool because the acid strips away a small layer of it each time you do it.
On average, the first time performing an acid wash can take two to three full days between draining, cleaning, and refilling the pool. As mentioned earlier, acid washing is an extremely labor intensive project, and it removes a thin layer of your pool surface each time it's done.
Plaster Pools
An acid wash is a popular choice for removing tough stains from plaster and Pebble Tec pools. An Acid wash consists of a mixture of water and muriatic acid. The acid makes contact with the pools surface and gently removes a small layer, revealing a fresh layer of plaster underneath.
– You bet! We can acid wash a pool without draining the water or damaging the surface. Remember, many people mistakenly believe that acid washing is a 'cure all' for swimming pool stains. The truth is, it is not.
Hose down the entire area you want to wash, then use a plastic watering can to sprinkle your diluted acid onto the concrete. Brush the acid over the concrete with a push broom or a long masonry brush. Let the acid sit for 5-10 minutes, then rinse the area and scrub it with your push broom and neutralize the acid.
Health Effects
Eye contact with muriatic acid causes serious eye damage; repeated or prolonged exposure to corrosive materials or fumes may cause conjunctivitis. Skin contact causes severe burns; repeated or prolonged exposure to skin will cause dermatitis.
Acids attack concrete by dissolving both hydrated and unhydrated cement compounds as well as calcareous aggregate. In most cases, the chemical reaction forms water-soluble calcium compounds, which are then leached away.