When getting ready to paint or seal concrete, you may have run across something called Etching. Concrete Etching products are placed right next to the sealants and paints, so you might have guessed they’re connected. However, what is Etching? Should you be doing it?
Etching describes the process of using chemicals to prepare your concrete for paint or sealer. While etching used to be universally recommended, technology has advanced more recently. While Etching can still sometimes be useful, you will want to weigh the pros and cons, as well as consider alternatives.
Table of Contents
- 1 What Does Etching Concrete Mean?
- 2 What Does Etching Do to the Concrete?
- 3 Why Etch Concrete?
- 4 What Happens if You Don’t Etch Concrete First?
- 5 Do You Etch Concrete Indoors and Outdoors?
- 6 Is Etching Concrete Necessary?
- 7 What are the Pros and Cons of Etching Concrete?
- 8 Is Etching Concrete a Toxic Process?
- 9 Can Etching Concrete Go Wrong?
- 10 Is Acid Etching Concrete No Longer Recommended?
- 11 What are Some Etching Concrete Alternatives?
- 12 Alternative Chemicals
- 13 How Clean Does Concrete Have to Be Before Paint, Epoxy, or Sealers?
- 14 What Products are Great for Etching Concrete?
- 15 How to Chemically Etch Concrete (Step-by-Step)
- 16 How Long Does It Take Concrete to Dry After Etching?
- 17 Final Thoughts
What Does Etching Concrete Mean?
Etching concrete is traditionally the process of using a strong acid to prepare your concrete for paint and/or sealant. These chemicals serve two purposes: to clean the concrete very thoroughly, and to create tiny imperfections for the paint and sealant to attach to. Etching might also be used to refer to more modern techniques which accomplish the same thing without using harsh chemicals.
What Does Etching Do to the Concrete?
Etching solves the problem of paint having nothing to adhere to by thoroughly removing dust and dirt as well as creating small imperfections in the concrete uniformly across the surface. This ensures that the paint will form a strong bond across the entire floor. After being etched, concrete should have a sandpaper texture.
Many concrete surfaces are quite smooth, especially those meant for indoor spaces like garages. This is very aesthetically pleasing, but not very good for painting. Paint and Film Forming Sealants required something on the surface to attach to, or they will simply peel off.
Additionally, any dust or dirt on the concrete can interfere with painting by causing the paint to attach to the dirt rather than the surface. For this reason, it is important to rough up the surface and clean it off. Etching accomplishes both.
What Happens if You Don’t Etch Concrete First?
If you don’t etch concrete in some fashion, you will have peeling paint very quickly after application.
Do You Etch Concrete Indoors and Outdoors?
While Etching is usually done indoors, this is because we more often seal and paint our indoor spaces. If you are planning to seal or paint an outdoor concrete space, you should also prepare that surface in the same way you would indoors.
Is Etching Concrete Necessary?
Etching concrete in the traditional sense (with strong acid) isn’t necessary. However, you will need to do something to the concrete to prepare it for painting. I’ll go over more modern techniques that have started to replace traditional etching as well as the pros and cons of traditional etching techniques.
What are the Pros and Cons of Etching Concrete?
Let’s talk about the Pros and Cons of traditional Etching techniques, as well as what those techniques are. The pros are the single step process, as well as the effectiveness of the procedure. However, it has some severe cons. The primary ingredient in traditional etching solutions is quite dangerous.
Is Etching Concrete a Toxic Process?
Traditional Etching involves a very strong acid, usually muriatic acid. muriatic acid is a diluted form of hydrochloric acid. This is important to note because muriatic acid, like hydrochloric acid produces toxic fumes and can severely injure skin.
These fumes are typically not problematic in small doses, but in an enclosed space the fumes can build up, especially when spread out on a large surface. This will cause mild acid burns in the mouth, nose, throat, lungs, and even stomach. Any skin contact will also cause severe damage.
Can Etching Concrete Go Wrong?
Because muriatic acid is so strong, etching concrete in this manner can go very wrong. You can give yourself chemical burns both internally (fumes) and externally (spills). Both can be avoided with proper use of protective equipment, but they always remain a risk.
Is Acid Etching Concrete No Longer Recommended?
So, given the dangers of using muriatic acid to etch concrete, is it still recommended? Not unless you are an expert. While this method is very time efficient, cheap, and thorough, it also carries too much risk to be preformed by novices. Unless you have substantial experience working with chemicals and hazardous materials, I would steer clear. Additionally, its never a good idea to use muriatic acid in a poorly ventilated area.
What are Some Etching Concrete Alternatives?
Now that I’ve provided my words of caution, lets talk about some alternatives to traditional muriatic acid etching. There are typically two types of alternatives – machine methods and alternative chemicals.
Instead of using acid to etch your concrete, you can use good old fashioned elbow grease. There are many tools on the market that can rough up your concrete, and then you can use any solvent cleaner to further prepare it for painting. The two most common tools are the handheld grinder or the industrial grinder. Either one runs the risk of making the surface uneven, so hiring a professional grinding team might be in your best interest.
The cheapest but most labor-intensive method is hand grinding. This is very similar to sanding a surface, so you can imagine how much time it will take to accomplish your project. A hand grinder is a small handheld machine with diamond grinding discs. These discs grind off the top layer of concrete to expose the rougher layer underneath. To get a good paintable surface, you’re aiming for something between 60 and 120 grit sandpaper in texture.
An Industrial Grinder is much larger than a Hand Grinder. This makes it less time and labor intensive. However, you still need to uniformly grind off the top layer, which can be tricky with a large machine. If you let it stand longer in one spot than another, you will have an uneven surface. It also requires a fair amount of strength to move around, as it is heavy. I wouldn’t suggest this method unless you can comfortably care at least 50 lbs. if not more.
Part of the problem with muriatic acid is the strength of the acid and its fumes. Weaker acids or alternative delivery systems run a lower risk of causing injury, and their effectiveness is still quite high. Because the acid is weaker, you may need to allow more time for these methods than you would with a traditional muriatic acid, but they will get the job done. The main benefit of choosing a chemical method is that it is less labor intensive.
These Tek Gel products are the most like muriatic acid in results. In fact, it still contains hydrochloric acid. However, it suspends the acid in a PH neutral gel. This has the effect of completely eliminating fumes and lowering risk of injury. Additionally, it is safer for the environment and can be hosed or vacuumed off the surface after use. It is more expensive than liquid acid, but the expense might be worth it to you if you want the best results without the danger.
Phosphoric acid is substantially safer than hydrochloric acid. It is only slightly weaker but has no fumes to speak of. When applied, make sure to use gloves.
Citric acid is by far the safest chemical option. It poses no risk in household use and has a pleasant scent. However, it is also much weaker than other alternatives, and may not be as effective.
How Clean Does Concrete Have to Be Before Paint, Epoxy, or Sealers?
Concrete needs to be very clean before paint, epoxy, or sealants are applied. Anything you miss will be trapped in the paint or clear coat until it is stripped off, so don’t be afraid to be picky. Get your floor as clean as possible before applying anything to it.
What Products are Great for Etching Concrete?
So, if you’ve decided to use chemical etching techniques, you might want to start thinking about products. There are many muriatic acid-based products as well as alternative acids like those discussed above. Some of my top recommendations are:
Rust-Oleum has one of the most highly rated products on the market. You can also buy their whole system to degrease, clean, etch, and seal your concrete. This is a typical muriatic acid solution, so all my cautionary words about protective gear and ventilated areas applies.
Seal-Krete is a less hazardous option for etching your concrete. It is a phosphoric acid-based product, which doesn’t have the fuming issues that hydrochloric acid does. However, it is still quite a bit stronger than citric acid. As a result, you will get consistently better results but should still use gloves and avoid skin contact.
Krud Cutter isn’t technically a concrete etcher. However, it’s a concrete cleaner that I kept coming across in my research. People really seem to rave that it cleans any and everything off their concrete surfaces. Since not ever etching technique/product is a combination cleaner and etcher, I thought mentioning it might be useful.
How to Chemically Etch Concrete (Step-by-Step)
Now that you’ve weighed your options and selected your products, lets go over how to use them. This is general advice and should be confirmed with the directions on your product.
1. Before you begin, check to make sure that you have:
- Protected the surrounding area from contact with the acid. Otherwise, you may “etch” unintended surfaces.
- Read your local regulations on disposal of hazardous materials.
- Gotten gloves and (if using a fuming acid) a mask such as an N95.
2. Ventilated the area appropriately
3. Chosen acid resistant or plastic containers for holding the product.
4. Now, you can begin the etching process. First, your product will likely need to be diluted with water. The ratio will be somewhere on the product or included insert. Remember: always pour acid into water, not the other way around. This reduces the risk of splashing or spillage.
5. Once the product has been diluted, you can spread it across the surface you are etching. Common ways of doing this are via spray bottle, mop, or painting it on.
6. After the surface has been coated, scrub it lightly with a scrub brush or push broom.
7. Leave the product sitting on the floor for the suggested amount of time (provided by the manufacturer). This is usually 10-15 minutes.
***** If your product does not require neutralizing, then skip to step 9 *****
8. While waiting, you can prep the neutralizer. Follow any mixing directions, then load into a spray bottle.
9. Neutralize all the containers and tools used in the process.
10. As soon as the waiting time has elapsed, apply the neutralizing agent with a spray bottle to the surface. Let it sit according to manufacturer directions.
11. Hose down all the containers and tools used 2-3 times with a garden hose.
12. Hose down the etched surface with a hose as well. Do this very thoroughly, as remaining acid can interfere with the sealing or painting process.
13. Let the concrete dry thoroughly before moving on with your project.
How Long Does It Take Concrete to Dry After Etching?
After you complete the etching process, you should let the concrete completely dry. This will take about 24 hours. However, if you aren’t seeing the concrete dry, you may need to ventilate the space to encourage the process.
In short, I do not recommend traditional concrete etching methods unless you are experienced with hazardous materials. However, you do need to do some form of etching to your concrete before painting or sealing it. Otherwise, you will end up with peeling. You can achieve this with either an alternative acid, or with a mechanical grinder. Either option is much safer.
Read my related articles: