Preparing a concrete surface before being coated with any product is a crucial step to the entire installation process. It can differentiate between a successful, high-quality outcome and a botched one.
Think about it. Before you wash your hair, you have to make sure it’s first been saturated with water. If not, the shampoo isn’t going to lather, clean your hair properly, and give you the outcome you are looking for, right?
The same goes for prepping a surface for a concrete coating.
There are two mainstream ways a concrete surface is prepped to be ready for a coating: acid etching and grinding. These techniques are meant to level the concrete and provide a smooth and even surface.
However, they are two vastly different techniques that differ in how they work and how successful they are in preparing the surface.
Southwest Exteriors has been an exterior remodeling contractor in San Antonio since 1989. One of our expert services is industrial-strength concrete coatings from Penntek.
We coat garage floors, sidewalks, driveways, patios, industrial kitchens, bathrooms, and just about anywhere a concrete surface is. When we prep a concrete surface for a coating, we use a 600-pound diamond grinder to properly grind the concrete to a smooth and even surface.
Although we do not use acid etching to prep concrete surfaces, we want to provide you with an unbiased comparison of the two to understand which may yield the best results for you.
This article will outline the pros and cons of acid etching and grinding as preparation techniques for a concrete surface so you can better understand the differences between the two.
After reading, you will know more about how each technique affects the concrete and the outcome of the concrete coating. Then, you can go into your project more educated and confident in the installation.
The Pros and Cons of Acid Etching Concrete
Acid etching concrete is a technique that consists of mixing water and acid, typically hydrochloric acid, to create a solution that is then spread across the concrete surface.
The point of the water and acid mixture is to remove any sheen on the concrete to create a raw surface that allows the coating to bond better with the concrete. Acid etching can also be used to simply clean a concrete surface to give it a fresher look.
By briefly describing acid etching, you can probably already start to see some pros and cons to this technique, so let’s get into it.
Benefits of Acid Etching Concrete
1. Acid etching is a quick process
The first benefit of acid etching your concrete is that it is quick. The process consists of dampening the surface, mixing and applying the acid wash, scrubbing the concrete with the acid wash, neutralizing the solution, then rinsing it off.
Acid etching can take less than one hour, depending on the skill level of the one doing the etching. However, it is recommended that the concrete surface dry completely before applying any coating on top, which could take at least two days.
2. Acid etching is inexpensive
The second benefit of acid etching concrete is that it is fairly inexpensive. You can find etching kits for around $75-$150.
There are even DIY solutions to gathering your own ingredients and creating the proper solution on your own for much less than that.
3. Acid etching allows you to DIY it
Acid etching is most popular around the DIY concrete coating community because of both of these benefits. You can find etching and concrete coating kits to do the entire process yourself.
So, if you’re looking to prep your concrete surface to aid your DIY coating, acid etching is a viable solution.
4. There is no dust debris with acid etching
The final benefit of acid etching is that there is no dust flying around like grinding concrete. Dust flying around can create health issues if inhaled and settle in hard-to-reach areas.
This is just an overall inconvenience with grinding concrete, so you won’t have that problem with acid etching.
Drawbacks of Acid Etching
1. The chemistry involved can be difficult
Although the acid etching process is a fairly simple step-by-step process, the chemistry involved can be difficult.
You must mix the acid and water at the proper ratio, and they must be mixed in the correct order. If you struggled in chemistry class in high school, you might want to get a helper or supervisor for your project.
2. Acid etching can be dangerous
While the chemistry of acid etching can be difficult, it can also be dangerous. Not only are you dealing with chemicals in the first place, but if the mixing directions are not followed exactly, you can cause a reaction that can be harmful.
If you decide to acid etch your concrete, you must ensure you have the proper protective gear to do so, like gloves, safety glasses, and making sure your body is fully covered. If not, then you potentially risk chemical burns or worse.
3. Acid etching has negative environmental effects
Another major drawback of acid etching is its negative environmental effects, which is why acid etching is not so popular anymore.
When the acid solution is poured over the concrete surface (and especially when it’s washed off), the runoff of that solution can go into the nearby dirt or grass and harm the environment because it is a chemical solution.
This can cause erosion in the soil and harm the plants and animals in the area.
Is acid etching concrete a good solution for me?
Now that you know the pros and cons of acid etching concrete, you can better know if this is the technique you want to use to prep your concrete for a coating.
If you are DIY-ing a concrete coating, acid etching may be a good solution for you. It’s inexpensive and very DIY-friendly, so you can find many step-by-step guides online to help you with the process.
However, you must be aware of the safety and environmental risks of acid etching.
Benefits and Drawbacks of Grinding Concrete
Grinding a concrete surface to prepare it for a coating is another most popular technique used mostly among professional contractors. It consists of using an industrial grinder with a diamond sander specifically fit for the hardness level of the concrete.
Like with acid etching, there are a few pros and cons to grinding a concrete surface. We’ll outline those pros and cons here.
Benefits of Grinding Concrete
1. Grinding creates an ideal, smooth, and even concrete surface
The first benefit of grinding concrete is that it creates the most ideal and smooth surface for a coating. An industrial concrete grinder is a professional tool. This means that it is mainly used by established contractors who know what they are doing.
Concrete must first be tested for hardness to find the correct diamond that will grind the surface without damaging it. You can compare grinding the concrete to sanding a rough piece of wood. It will leave the surface smooth and will also strip any laminates off so the coating can better bond to the concrete.
2. Grinding doesn’t take long
The second benefit to grinding a concrete surface is the time frame. Obviously, the time it takes to fully grind the area depends on the size of the area.
For example, a double-bay garage can be fully ground by a professional contractor in under two hours. While, compared to acid etching, this may seem like a long time, it is a small fraction of the entire project time.
3. No waiting period between grinding and applying the coating
The third benefit of grinding concrete is that there is no waiting period between grinding the surface and applying the coating.
When concrete is etched, you must wait until the concrete is fully dry before applying the coating. This can take days. Grinding a concrete surface and applying the coating can happen on the same day, making it a huge convenience for your project timeline.
Drawbacks of Grinding Concrete
1. It’s not really DIY friendly
As mentioned before, using an industrial grinder for concrete is mostly used among professionals. Chances are, you do not want to spend thousands of dollars for a 600-pound grinder that you may only use a handful of times.
This means that if you were hoping to DIY your concrete coating project, grinding the concrete to prep it is most likely not a viable option.
2. A high level of expertise is needed
Another drawback of grinding concrete is that a high level of expertise is needed to do it properly. When concrete is tested for hardness using the Mohs hardness scale, the hardness level of the concrete will determine what type of diamond is needed to grind it.
If the wrong type of diamond is used to grind concrete, it can damage the concrete if it is too soft or not grind it enough if a smoother diamond is used. If this happens, it can cost you more time and money to have your concrete repaired or ground with the proper diamond.
This is why it is crucial to find a contractor you can trust with your project. Knowing what goes into the preparation of a concrete coating will allow you to ask the right questions and determine if a contractor will meet your needs.
3. Dust can accumulate after grinding
Unlike acid etching, the last drawback of grinding concrete is that dust is an inconvenience. Some contractors have a special vacuum attached to the grinder to suck up as much concrete dust as possible. However, sometimes it can’t get it all.
In outside areas, dust could accumulate on nearby plants or animals. Indoors, it can make its way to high surfaces or areas you don’t dust much. Dust from grinding the concrete is mostly a problem for the contractor doing the grinding, but it is something to consider for the cleanliness of your home.
Is grinding concrete a good solution for me?
Now that you know the pros and cons of grinding a concrete surface to prepare it for a concrete coating, you can consider if this is what you are looking for.
If you hire a professional contractor for your concrete coating, chances are they will grind the concrete in preparation. This is because grinding the concrete creates the most ideal and smooth surface for a concrete coating. But, you must make sure you choose a contractor that knows what they are doing.
If you are looking to DIY your concrete coating, grinding the concrete is probably not a plausible solution.
Acid Etching vs. Grinding Concrete: Which is better for me?
After outlining the pros and cons of acid etching and grinding concrete, you can better understand which solution might be best for your project.
If you want to DIY a concrete coating, then acid etching is the most viable solution for you. While it may not be necessary, it can help even the surface and prepare it best for the coating to adhere to the concrete.
If you want to hire a professional contractor for your project, they will probably grind the concrete and recommend it as the better option for your coating.