Preparting Concrete For Epoxy
7 Most Common Questions Answered:
Epoxy Coatings have become an increasingly welcome solution to flooring. Because Epoxy ticks all of the boxes for being affordable, functional and aesthetically pleasing they can be a good fit for any setting. A very appreciated solution to flooring for residential, commercial and industial buildings. With its popularity growing, lots of people started to consider replacing their traditional flooring system. Furthermore, there is lots of room to display custom creativity.
However, the mistake many people make is to ignore the preparation part of the process and directly dive into pouring the resin. As you can imagine, the result is, well, unsatisfactory.
Because of that, today I want to answer seven of the most common questions people who are installing epoxy flooring have. So let’s begin!
1.) Why does Surface Preparation Need to be Done Before Applying Epoxy Coatings?
A very simple statistics say that more than 90% of the epoxy coating projects fail due to incorrect surface preparation. The explanation for this fact is actually very simple to understand. Think about the epoxy coating as you would think about paint.
I mention this because it acts like paint and due to that, you need to prepare your working space accordingly. By correctly prepping your surface before applying the epoxy coating, you ensure a successful adhesion.
Applying epoxy can be done on multiple materials such as metal, wood, drywall, tiles and of course, the topic of the day, on concrete.
Regardless of the surface, you wish to work on, the recommendation remains the same – prep your working space!
Before we go and talk in-depth about how preparing concrete for epoxy will save you lots of possible future problems, I wish to take a minute or two to shortly explain the need for preparation when handling all the surfaces mentioned above.
METAL
Metal is one of the most problematic materials when it comes to oxidation. This is why they need special attention. Even if prepped, the risk of rust is very high, so you need to act really fast in applying the coating.
WOOD
On the other hand, wood is very porous and flexible and therefore other reasons for thorough preparation are in discussion. Without an attentive cleaning, followed by a sanding technique, the surface won’t be able to provide the necessary bond profile for your next layer, hence you should expect a poor result.
Even though for an unknowing eye it is hard to comprehend, drywall is actually similar to wood when talking about porosity level. The reason for this is because it has a thin layer of paper covers, known as gypsum. Because of that, just as discussed earlier when talking about wood, attentive preparation is required for satisfying outcomes.
TILES
Regardless if we are talking about ceramic or quarry tiles, the need for preparation is in order. They need to be cleaned and also sanded to ensure a successful coating. However, you need to be extra careful with the sanding because the particles created during this process are essential.
CONCRETE
Last, and most definitely not least, it is time to talk about the importance of preparing the surface before applying epoxy on concrete. It is the most common surface to work with and because of that more than one technique can be applied.
However, by far the best results come from grinding and we will detail this aspect in the next part of the article. For now, I want to say that when it comes to this kind of surface, all experts say that in order to have a successful application of epoxy you need to prepare your concrete to be what is known as CSP-3 (Concrete Surface Profile), name given by the ICRI (International Concrete Repair Institute).
If you do otherwise, you will most probably find yourself in an unfortunate situation.
2.) Why is Surface Grinding the Best Way to Prepare Concrete for Epoxy Coatings?
As discussed, if you decide to coat your concrete with epoxy, you need to prepare the surface first or you won’t have a very pleasing outcome. As mentioned above, this prep can be done in more than one way.
One of the used methods involves chemical strippers, while the other one is mechanical and involves something called surface grinding, which is by all accounts the most effective and I will explain why.
Advantages
For starters, even though chemicals have been proven to be also effective, floor grinding offers a very big advantage when it comes to opening the pores of the concrete. The reason why this is such an important fact is that opened pores will help the epoxy to find something to grip on and therefore will create a more trustworthy adherence.
I am sure that among the readers there are people ready to argue that chemicals can do this just as good, and I will not argue on that level. I will, though, say that no chemical can create such an even surface as grinding will. Because of that by grinding the concrete you will even smooth out any imperfection your surface might have to begin with.
3.) How Much Grinding is Needed to Prep a Surface for an Epoxy Coating?
I hear this question a lot when discussing grinding and I always offer the same answer. Each case is different and you need to check your concrete while working on it.
You will see that the grinding has more levels and it all depends on how smooth you want your surface to be. However, you should keep in mind that you are preparing the surface for coating and are not polishing it. Your target should be to have a more granular look than a complete polished one.
4.) How Much Will a Concrete Grinder Remove?
Again, this question can receive different answers, because truth be told, by grinding a concrete floor you can remove as much concrete as you need to remove.
As discussed earlier, you remove one layer of concrete at a time. So, depending on what you are working with, you should expect to remove somewhere around 1/16″ of concrete.
Of course, there are grinders that can remove even up to 1/8″ in just one pass, but again this is a variable given by the tool you are using. So, my advice to you is to check the specification of your device and work with it accordingly.
5.) How long does it take to grind concrete?
Many people ask this question, but unfortunately, there is no exact answer to it. First of all, you need to make sure that if there is any crack, pit or other imperfection in your concrete, you
repair it. You need to remember that not even grinding can remove oil stains, so if you have any be sure to eliminate it.
If you choose a wet concrete floor grinding, you need to wet the surface and only then move the machine you are using in a circular way. The process of figuring out the amount of time needed to finish the grinding should not take more than a few minutes.
You will need to check your work constantly and to do that, I recommend you use a hose that has a pressure nozzle. Using it, spray the area and run your fingers on the surface you worked on. Don’t stop until you feel the area you worked on as medium-grit sandpaper.
As I said at the beginning of this point discussion, an exact time cannot be given. Each grinding concrete needs different time and each person works at a distinct pace. However, for a 400 ft² space, you should expect to finish the work in somewhere around two-two and a half hours.
6.) Can you grind 'NEW' concrete?
Well, technically yes and no. It depends on what you understand when you say “new concrete”. If you are referring to freshly poured concrete, then the answer is “NO” you cannot grind it.
The concrete needs 30 days after placement to be ready for the grinding technique. The reason for this is because, before that, the surface is too porous and soft, so the idea of grinding is not the best one.
This being said, if you are referring to a one-two months old concrete as being new, then the answer is “YES” you can grind it and prepare it for the epoxy coating.
7.) What is cross-hatching?
This term comes from drawing and it reflects the technique of using fine parallel lines that are drawn very closely together for the purpose of creating a specific shade or texture.
Similarly, when talking about concrete grinding, cross-hatching is about cutting and polishing passes which are made at a 90-degree angle to the previously made linear passes for the purpose of creating texture and different layers.
More so, this technique will help you to avoid creating visible lines on your floor and refine the whole process.
Conclusion
The conclusion is simple and I don’t want to take more of your time. The resolution is – you need to carefully prepare your surface before anything else. Furthermore, if you intend to work with concrete, you should most definitely take into consideration the mechanical approach of grinding the concrete surface.
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Ronald Wesley
CEO MOY FLoorFX
Hello I’m Ron, CEO of MOY FloorFx, South Central Pennsylvania’s Epoxy Distribution and Training School. I’m here to support you by getting you the right product and instruction for your floor coating business.