How To Acid Wash Or Acid Etch Concrete

Tiles and marbles are way too common now; trust me because I’ve concrete flooring in my driveway and courtyard. 

It is good, but too plain Jane, in my opinion. And as you know, I am a picky perfectionist who’s always on the hunt for a new project.

I was fed up and decided my boring concrete flooring just had to go because its time was up. But a dilemma of what to replace it with struck me hard. Entirely uprooting and installing a new floor from scratch, just because I was bored of it, seemed like a drag.

I pondered over it and found a balance in the situation. After realizing that simply changing the paint and texture will do the job, I was all set for the project. 

But you should know that before painting, it is crucial to acid wash the concrete. So, today, I will tell you how to acid wash or acid etch concrete through this informative guide. 

Hi! I’m Stacy Smith and let’s get started.

What Is Acid Etching?

Concrete acid etching or washing is the process of applying a diluted acid solution on the floor to open the pores and roughen the surface. It makes the floor susceptible to new coatings of paints and sealers to provide better adhesion.

You can also carve patterns on the concrete surface by etching it. This process is essential if you want the paint to last long on the floor. The open pores let the coating bite firmly onto the surface, thereby making it long-lasting. 

Also, acid-etched floors have remarkable color enhancement properties and appear more vibrant than most floors. 

How To Acid Wash Your Concrete?

I should warn you beforehand that washing requires the use of acids that have corrosive properties. The process is risky and toxic for plants, metal pieces, and people in general. 

If you are doing it indoors, then noxious fumes will be generated, which can be dangerous. My advice is to do it under professional guidance and by taking proper safety measures.

Types Of Acids Suitable For Etching

There are several products on the market that are specifically designed for acid washing. Some contain mild chemicals that are non-toxic, while others are a blend of acids like phosphoric and muriatic acid.

These specialized products are safer than hardcore acids and release lesser fumes, which makes them eco-friendly. Plus, they don’t require any neutralization. 

Now, I’ve shortlisted the following acids as the most suitable for the procedure:

1. Citric Acid

Widely utilized in the food industry, citric acid is extracted from citrus fruits like oranges and lemons. It is the slowest alternative for etching since it is a weak acid, however, it’s the safest to use because of its prolonged reaction time.

2. Muriatic Acid

The most effective and common among all types is muriatic acid, a crude version of hydrochloric acid. This powerful acid is perfect for clearing mortar and rust from masonry. 

I must warn you to be careful while working with it since it’s the most notorious and harmful out of all acids. For instance, it can erode metals and burn skin or fabric.

3. Phosphoric Acid

Typically used as a food additive, this weak acid is another safe yet effective option for etching concrete. However, it is a little too slow and isn’t readily available.

4. Hydrochloric Acid

Hydrochloric has a short reaction period and is ideal for various projects, giving neck-to-neck competition to muriatic acid. You can use it for treating swimming pools, producing batteries, and processing steel. 

But do remember that it is just as toxic as the former and should be handled with extreme care.

Step By Step Guide For Acid Etching

Follow these easy steps to acid wash your concrete floor.

Step 1: Prepping Up

First and foremost, clean the concrete surface thoroughly, removing the oil stains and grease. You can do this using an alkali detergent because the acid won’t work properly if the water forms beads on the floor. That’s why complete degreasing is crucial.

Step 2: Dilute The Acid

All the dilution and mixing should be carried out in a plastic bucket because it is resistant to lower concentrations of acids. 

First, take some water in the bucket at room temperature and slowly pour the acid into it. Make sure that you go about it at a snail’s pace because hasty pouring can lead to a violent reaction. Also, check the product description to ascertain the correct ratio. 

Muriatic acid generally needs three to four parts of water per part of acid. What’s more, phosphoric acid should be used only after twenty to forty percent dilution.

Step 3: Applying The Acid

Clear all the furniture from the area and gently dampen the surface by sprinkling water. The surface should stay drenched all the time but make sure that you don’t puddle it. 

Additionally, cover the drywall and asphalt with some cloth or barrier before dividing the area into multiple small sections, reserving one section for testing. Proceed, to spray the acid using a watering can, preferably plastic, while keeping the nozzle close to the ground. 

Next, you need to brush the acid evenly and create a smooth layer. You can either do that manually using masonry brushes or use a floor machine.

Step 4: Washing And Neutralization

Leave the acid undisturbed for five to ten minutes while it washes the concrete. Once that is done, rinse and clean the floor thoroughly with a generous amount of water and a long brush. 

Lastly, neutralize the acidic conditions using some alkali mixture.

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