To Acid Etch Or Concrete Grind Is The Question

he flooring industry's Big Bang question is whether to acid etch or grind the concrete slab. Both methods of concrete preparation have supporters and critics.

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Correct concrete preparation is the key to your new epoxy floor's long and happy life. Correct preparation means that the concrete pores are open enough for the epoxy to bond with the concrete and right surface profiling has been achieved.

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Insufficient concrete preparation is the number one reason for epoxy failure, a short and miserable life span, and tons of wasted money.

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We prefer concrete grinding as a preparation method, but we will discuss both methods to determine which one you prefer.

What Is Acid Etching The Concrete?

For years, acid etching or acid washing has been the preferred process of concrete preparation. It involves applying hydrochloric/muriatic or buffered phosphoric acid to the slab, followed by cleaning and rinsing the concrete with water after the etching reaction has been completed.

Why wash it with water? Well, we weren't experts in chemistry at school, but in this case, water neutralizes the acid wash solution.

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Putting chemistry aside, acid wash works by eating through and removing the top surface of the concrete; some even say it achieves the same result as concrete grinding.

Does Acid Etching Work?

Let's face it: Throwing some acid on the concrete floor, waiting for it to do its magic, and then rinsing it off with water sounds like a kid's play.

Why don't more people do Acid Etching, then?

Well, there are a couple of reasons, really. The main one is acid washing, which does not work as well as concrete grinding.

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Acid etching works by reacting with the free limestone in the concrete. However, if there is oil, dirt, or grime on the concrete surface, the acid etching will simply not be enough.

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If not washed and removed properly, the acid can clog the concrete pores by creating a wet concrete dust film. This, on the other hand, will interfere with the epoxy and its bondage to the concrete slab, eventually leading to the epoxy peeling off.

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If the acid is left on the concrete for longer than necessary, it can overexpose the concrete pores. Over-etching the concrete floor can inject water and moisture into the slab when the acid is washed off. This will trap moisture underneath the epoxy and ultimately shorten its lifespan.

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Finally, acid washing can damage pavement, stones, and grass if not done carefully. In many places, regulations regulate how to handle and clean acid so it does not affect the environment.

To conclude, acid etching can be unpredictable and unreliable, even when done by a professional. Many epoxy manufacturers do not recommend using acid etching as a concrete preparation method.

What Is Concrete Grinding?

Now, let's talk about the bad boys of flooring preparation.

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Yes, you guessed it right! It's the concrete grinders.

Concrete grinders use different attachments to grind and level the concrete. These diamond attachments remove all dirt, oil, grime, and grainy compounds on the surface (acid cannot remove it) to create a clean and smooth surface.

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As every concrete is different in terms of texture, composition, and hardness, alternating between different grinding heads helps achieve the desired surface.

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When starting the grinding process, the flooring expert will start with a low grit of 30 and move up to 60/80 grit until the concrete is ready for the epoxy application.

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Between each grinding stage, the concrete is vacuumed to ensure no dust is lying around.

Concrete grinding provides more precision and control over the surface, and the professional preparing your floor can get the exact texture they need.

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We say this a lot, but concrete texture can be the difference between a happy decades-old epoxy and a sad peeling-off after one year of epoxy.

Concrete Floor Preparation Conclusion

If you decide to do your floor by using a DIY kit, we beg you not to use acid washing. We want to save you money.

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If you are confident with your capabilities, you should rent proper grinding equipment suitable for the job.

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Bear in mind that you will need to think about how to know you have the right texture and how to control the concrete dust that is flying around.

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If you hire a contractor to install your new epoxy floor, make sure they diamond grind the concrete.

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An epoxy flooring contractor that acidizes the concrete may need to cut corners to cut expenses and will likely not offer a high-quality floor finish.