Do you need to sand concrete before epoxy?

If you’re new to epoxy and haven’t used it before, this article will introduce you to the basics. We’ll go over why you need to sand concrete when using epoxy, which sander is best for your project, some tips and tricks for sanding concrete successfully, and how to ensure a good bond. So let’s get started!

Do you have to grind concrete before epoxy?

You don’t have to grind concrete before epoxy. However, it’s strongly recommended that you clean your concrete with soap and water before applying an epoxy coating.

Some people will degrease the floor first, while others prefer to use a pressure washer. You can also use a floor buffer to clean your concrete before applying an epoxy coating.

Once it’s cleaned, let the concrete dry completely so you have a stable base for your epoxy. If there are any cracks in the concrete, repair them by filling them in with putty or sanding them down flush to the rest of the surface.

Do I need to sand before applying epoxy?

Concrete should always be sanded before the application of a floor epoxy. Sanding gives the epoxy something to grab onto, so it will last longer and provide a better level of adhesion.

Before applying an epoxy sealer, you want to make sure that all loose particles are removed and that there is no dust on the surface.

The best way to sand concrete is with a sanding machine and 80/80 grit diamond sander tooling. This process can also be done by hand using 150 grit sandpaper. However, this method can take longer than using a machine to get the same results if you are working on a large area such as a garage floor or warehouse floor.

Wire brushes should not be used because they do not remove the top layer from the concrete like sanding does, and dust cannot be removed with this method. Sanding also removes any existing sealer in order for your new sealer to adhere properly.

Does concrete have to be smooth for epoxy?

You don’t necessarily have to sand concrete before epoxy. If the surface is rough and porous, you may need to grind it down first to make the floor smooth enough for an effective application.

Unless you’re skilled at using a concrete grinder and identify your project as a challenging DIY endeavor, it’s best to consult with a professional before proceeding with your plans. Consulting is free, while poor application can be costly—the consequences include bubbling, peeling, and blistering during curing time or eventually in the future.

Can you epoxy over old concrete?

The short answer is: yes.

While you may be able to epoxy over old concrete, it’s best to rough up the surface and clean it thoroughly before doing so. If you don’t prepare your garage floor properly and lay down a solid base for the epoxy, then it could end up peeling off fairly quickly.

But here’s the thing—it’s well worth the effort to do so! Epoxy is durable and can increase the longevity of your garage floor by decades. It also protects against pitting and staining, meaning that even if something does spill on it, it’ll be easy to clean off.

How do you prepare concrete for epoxy?

The first step to getting concrete ready for epoxy involves a thorough cleaning. Use a pressure washer to remove any dirt, grease, or debris from the concrete surface.

Old paint, stains, and other coatings need to be removed as well for a smooth application of your new floor coating. A paint scraper or chemical stripper works best for this. Once you have removed the old coating, give everything another pressure washing with water to get rid of any remaining paint chips or other debris. It’s very important that the concrete is completely dry before applying epoxy, so let it air dry thoroughly before proceeding.

If there are cracks in your concrete slab, fill them in with a patch product made specifically for concrete. This will prevent moisture from seeping in behind the epoxy coating on your floor and causing problems down the road such as rusting metal reinforcement bars and loose floor tiles if you have them installed over your slab.

Lastly, you want to make sure that all dust is removed from around the edges of the room where you’ll be installing epoxy. You can use a shop vacuum with an attachment wand to get into hard-to-reach places like corners and along walls where dust may have settled out of reach of your power washer spray pattern during cleaning.

How do you prep concrete for epoxy?

Once your concrete is clean, you need to prep it for the epoxy by following these steps:

  • Apply a concrete etcher/degreaser. You can apply this with any simple garden sprayer. Just make sure that it’s cleaned and rinsed out thoroughly from anything else you may have used it for! If you’re using a two-part degreaser, mix them in the sprayer first. Then just spray your entire floor very liberally, making sure you get every inch of the floor wet. Scrub lightly with a stiff bristle brush to work in the degreaser and to help release dirt and grime from pores in the concrete. Rinse thoroughly with water after degreasing scrubbing and rinse again once all of the suds are gone to ensure there is no residue left on your garage floor before applying epoxy paint.

How do you prepare surface for epoxy?

Here are the steps you need to take when preparing your surface:

  • Clean and dry the surface.
  • Check that it is smooth and intact.
  • Make sure that it is free of contaminants, dust, moisture, adhesives, and paint. If a crack is present make sure it’s been repaired prior to applying epoxy.

How long do you have to wait to sand epoxy?

How do you know when it’s time to sand epoxy? You need to wait until the epoxy is fully cured, which can range from one to five days depending on the type of epoxy and conditions in the room.

The best way to test whether an epoxy is ready for sanding is with a fingernail test. Gently press your fingernail into the surface. If it leaves a mark, the coating hasn’t completely cured. Keep waiting!

If you sand too soon, you risk lifting off some of the first layers and exposing bare concrete beneath. This means that your second layer won’t adhere properly, which can lead to peeling or even bubbling. Sanding too soon will also leave noticeable imperfections and make for an uneven finish—and no one likes that!

You should also consider temperature and humidity when deciding how long to wait after applying epoxy before sanding. A cold garage in winter will slow down curing compared to a warm basement in summer. The same goes for high humidity; this slows down curing time as well. In these cases, cure times could double or even triple what they are under ideal circumstances!


Nowadays, people are becoming more and more aware of the benefits of epoxy for concrete floors. However, there is still a lot of confusion about how to best prepare the surface before applying an epoxy coating. Hopefully, this article will give you some clarity on that topic and will help you make an informed decision.

As we have seen, sanding concrete is not necessary in all cases. Depending on the condition of your concrete floor, other procedures might be a better option. The right choice depends on many factors: what kind of look you want to achieve, how much time and money you’re willing to invest, etc. If you have any questions or doubts about your own situation, it might be worth consulting with a professional contractor before starting work on your floor.

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Martin Flood

Martin Flood has been working in the construction industry for over 20 years as a general contractor with expertise in remodeling projects that are large or small. He has furthered his career by specializing in epoxy resin flooring, providing excellent service to both commercial and residential clients. Martin’s experience enables him to offer professional advice on how to choose the right type of project based on your needs and budget.

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