New and old concrete is often sealed to help protect it from the elements and salts, improve durability, enhance beauty, and prevent mold so it lasts longer. So, if you’re considering painting the concrete of your garage or basement floor, outdoor patio, or sidewalk, you may wonder, can you paint over concrete sealer? If you are, we’re here to help!
Most concrete sealers bond to the concrete by filling and gripping the pores, making it almost impossible for paint to adhere properly. These sealers need to be removed or the concrete surface roughened by sanding, grinding, or etching. However, some water-based sealers will allow paint to bond.
In this guide, we’ll discuss whether you can paint over a concrete sealer. Whether to seal concrete before painting or if you need to prime the concrete before painting. We’ll explain how to paint sealed concrete, and the right way to paint concrete. Plus, we’ll identify and review one of the best paints for concrete, best primers, and best concrete sealers so you’re better prepared for your concrete project.
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Can You Paint Over Concrete Sealer?
Concrete sealers are designed to penetrate up to 1/2” into the surface pores to bond with the concrete and prevent moisture penetration, which means paint won’t bond well. Prior to painting concrete, do a water drop test to see if the concrete has been sealed. Drip water in small amounts in various locations across the concrete surface to be painted. If the water beads and the concrete color doesn’t change or change much, it’s sealed. If the drips spread and absorb in, darkening the concrete’s color, it wasn’t sealed.
Sealed concrete can be painted, but it requires more prep work than unsealed concrete. Clean the concrete and remove oil and grease stains and excess sealant. Fill cracks, chips, and holes to create a smooth surface and grind down any raised imperfections.
Once that is all done, sand, grind, or etch the sealed concrete surface to roughen it and give it some grit or texture. Clean the concrete thoroughly and allow it to dry. Use a quality concrete primer to bond, seal, and smooth the roughened concrete prior to applying the paint topcoat.
Do I Need to Seal Concrete Before Painting?
Depending on the location and use, concrete doesn’t need to be sealed prior to painting, so if the plan is to paint the concrete, skip the sealer. A sealer fills the pores in the concrete to protect it from moisture damage, making it difficult for paint to bond. Plus, most sealers are clear or translucent if tinted, allowing defects and discolorations to show through.
Paint can be used outside on patios, decks, sidewalks, and on interior walls and floors. It is a surface coating, so isn’t best for abrasive or high-traffic areas, such as driveways. Concrete paint is available in dozens of colors too.
The paint is easy to apply, inexpensive and covers well. It not only hides stains but also other discolorations because it is opaque, plus it protects the concrete. However, applying a concrete primer prior to painting is important as it will create a better bond between the concrete and paint.
Do You Need to Prime Concrete Before Painting?
Priming is essential prior to painting interior or exterior concrete. The primer bonds to the concrete and makes a smooth surface for better paint adhesion. Primer is absorbed into the concrete pores helping to protect it from moisture and damage, which is why it is important to use a concrete primer.
The absorbed primer makes a smooth even surface by also filling in small voids, bubble holes, and gaps. Additionally, it helps prolong the life of the paint used for the topcoat.
How to Paint Sealed Concrete
Prior to painting a concrete surface, inspect it to determine if it is primed and what type of sealant was used. Concrete sealers can penetrate up to 1/2” into the pores to bond and seal the concrete, preventing moisture penetration, which means paint won’t stick well.
Do a water drop test to see if the concrete has been sealed. Drop small amounts of water across the concrete surface to be painted. The color of sealed concrete won’t change or change much, and the water will bead. If the drops spread and absorb in, the concrete color will darken, indicating that it isn’t sealed.
If the concrete has been sealed, then the type of sealer becomes the next question. Acrylic and epoxy sealers tend to resist bonding with paint and require more prep work before paint will stick. Water-based sealers breathe better, so paint will bond more easily with some surface sanding. Test a small area using lacquer thinner to determine if it has been sealed with a water-based, silicone, acrylic, or epoxy sealer.
Apply lacquer thinner to a small area of the concrete surface. If the sealer dissolves and begins to penetrate, then it is probably a penetrating solvent-based sealer. If the thinner has little or no effect, it may be a silicone or other unknown sealer.
Sealers that separate and leave rubbery, eraser-like particles or residue when treated with the thinner, are likely a water-based acrylic coating or surface sealant. However, if there is no change or reaction, then it’s probably a water-based penetrating sealer.
Identifying the type of sealer will help determine the next step. A solvent-based penetrating sealer can be resealed or ‘painted’ with a tinted (colored) penetrating solvent-based sealer. A water-based surface sealer or silicone may need to be stripped off.
Unfortunately, the residue in the pores may remain, so a tinted solvent base penetrating sealer may be required. If it is a water-based penetrating sealer, the pores will still contain sealer after stripping, so use a tinted water-based penetrating sealer tinted to your color choice. Some water-based sealers can be painted without stripping or sanding, try a small test area to see if the primer or paint will bond.
Alternatively, if you want the opaque quality of paint, give it some texture and grit for the primer and paint to stick to. Sand, grind, or etch the concrete surface to rough up the concrete, and then sweep or vacuum the surface. Use warm water with a degreaser added to wash the floor using a scrub brush to work the degreaser into the pores and any oil or grease spots.
Make sure there is plenty of ventilation. Rinse with water and let dry. Once dry, perform the water drop test again to check for moisture absorption. Use an appropriate concrete primer and paint for the desired finish – always follow the manufacturer’s directions for best results.
How To Paint Concrete: The Right Way
Painting concrete requires some prep work. Use the water drip test to determine if it has been sealed. If the water drops bead and the concrete doesn’t discolor much or at all, then it has been sealed. If the drops absorb and darken the concrete around them, it probably hasn’t been sealed. Whether the concrete has been sealed or not, the following steps will help produce the best paint finish.
Clean
Sweep or vacuum the concrete surface to remove loose materials and dirt. If it has been painted in the past, scrape off any loose paint and consider using a paint stripper to remove as much of the old paint as possible. Once it has been removed, use a neutralizer to wash off the stripper residue. If the concrete was or wasn’t painted or sealed, it still should be washed prior to painting.
To remove stains, oil, grease, salts, and other contaminants, use warm water with a degreaser with a stiff bristle scrub brush or broom. Once the surface is clean, rinse with clean water and let the concrete fully dry before moving to the next step. Alternatively, use a pressure washer. You may still need the scrub brush and degreaser for stubborn stains.
A paint stripper with a chemical base can be used to remove paint and/or concrete sealer. Apply the stripper and let it sit for the recommended time, then used a scraper to remove the residue. Work small areas that can be done in the time allotted, so the stripper doesn’t sit too long. It typically will require two coats to remove most of the sealer and paint.
Another way to clean the concrete is to use an acid wash to remove dust and rust. This is the best way to remove rust stains. However, if the floor has been sealed, the acid wash won’t penetrate to remove deep-seated stains. Additionally, the acid can damage the concrete if not properly applied and removed.
Whichever method is used, it is also recommended to wash the concrete afterward to ensure it is fully clean. Proper ventilation and protective coverings are also important. Concrete dust is a respiratory irritant to some, so a respirator may be helpful too.
Etch
Removing sealer from the pores of concrete is difficult to impossible as it can bond 1/2″ into the concrete. New concrete should be allowed to cure for 60 days or more prior to etching.
Etching will give the primer and paint something to grip. It will also remove concrete laitance (powdery concrete particles) and efflorescence (powdery chalk-like salt particles). However, etching is time and labor intensive and can be expensive, but it will provide the best surface for paint adherence and uniform paint color.
One method of etching requires the use of a sanding block, sander, or industrial disc sander or grinder depending on the size of the surface being prepared. Do an initial pass with a medium (150-grit) sandpaper and then switch to a fine (220-grit) for a smooth, even, paintable surface. This method produces a lot of dust, and is DIY-friendly, but can be expensive.
Another method uses an acid etching solution such as Seal-Krete Clean-N-Etch. Mix as per manufacturer’s instructions and apply to a workable area – 10ft x 10ft. Work the solution into the concrete with a stiff bristled scrub brush until it stops foaming, and wash with a strong stream of water. The surface should feel like a piece of 150-grip sandpaper. Smooth troweled surfaces may require a second application to achieve the desired feel.
Solutions used for etching typically contain hydrochloric acid, phosphoric acid, muriatic acid, or citric acid. While they won’t create dust and are DIY-friendly and less expensive, they can be toxic. Hydrochloric and muriatic acid produce fumes that can damage sinus passages and lungs, and the solution can burn skin and eat through fabric. Hydrochloric and citric acids are less toxic and more environmentally friendly, but also more expensive.
Once the surface has been etched, it should be washed clean and allowed to dry. Perform a water drop test in several locations. The drops should absorb quickly, otherwise do another pass with the sandpaper or etching solution.
Apply Primer
A primer should be used on concrete prior to the paint being applied. Use a water-based primer that has been formulated for use on concrete. These primers will bond well with etched or abraded surfaces, and can even bond to most water-based sealed surfaces.
Ensure the surface is clean and dry. Use a paintbrush to do around the edges and a roller or sprayer for the main surface. Remember to work toward an exit and not paint yourself into a corner. A second coat of primer is recommended after the first coat is fully dry.
A quality primer will bond with the concrete and improve the adhesion of paint, helping to prevent flacking. It also acts as a sealer to protect the concrete from moisture, stains, and other damage. Select a concrete or block primer, based on the location of the concrete, its use, and the desired finish – interior vs exterior, floor vs wall, high traffic vs low traffic.
Paint
Select the appropriate paint for traffic volume, use, location, and finish. Epoxy paint is strong and durable, so ideal for garages, carports, and other heavy traffic areas. Most interior concrete surfaces will finish well with regular interior or enamel paint. However, masonry paint will provide the best results.
A minimum of two coats is recommended, with a third being optional depending on color and finish. Allow each coat to fully dry before applying the next coat, and lightly sand with fine-grit sandpaper to improve adhesion. Let the paint dry for 48 to 72 hours before resuming regular use of the surface.
Seal
Once the paint has dried, an epoxy, acrylic, polyurethane, or wax sealant can be applied over the paint to further protect the concrete and paint, however, it is optional. If epoxy paint was used, a sealer isn’t required. Follow the manufacturer’s instructions for the best results.
What Is the Best Paint for Concrete?
The best paint often depends on the task. There are hundreds of different water-based acrylic-latex paints and epoxy paints, some work better for garage floors while others are better for porches, driveways, sidewalks, patios, basement floors, or interior or exterior walls. Some concrete paints even contain sand for a no-slip finish but aren’t ideal for where young children may play. Our pick is RUST-OLEUM Epoxy Shield concrete floor paint.
RUST-OLEUM Epoxy Shield concrete floor paint is a durable single-part interior-exterior self-priming one-coat acrylic paint. It is resistant to stains, chipping, UV rays, fading, weathering, oil, chemicals, and hot tires. One gallon covers between 300 and 400 square feet with a 1/2″ nap roller.
The battleship gray satin armor coating goes on smooth and doesn’t require a lot of prep work or sanding. It fills small cracks and chips for a solid carefree finish that won’t chip or flake. The finished floor is easy to sweep and messes clean up easily with soap and water.
Best Primer for Concrete
Concrete primers typically come in acrylic-latex, alkyd-oil, polyurethane, epoxy, and tinted shellac, plus tintable silane sealers. They are also formulated for interior or exterior use, or both. Plus, there are literally hundreds to choose from.
Acrylic-latex tends to soak into and bond well with concrete. It also dries more quickly while alkyd-oil primers don’t cure as quickly or bond as well. Polyurethane primers are better at covering up stains and other imperfections, while epoxy primers form a super strong durable bond. Silane sealers can be tinted and penetrate into the concrete to provide protection at any temperature. Select a primer that best suits the task.
Our pick is Zinsser Bulls Eye 1-2-3 Primer for interior and exterior surfaces. The water-based, tintable, stain-blocking acrylic one-coat primer will penetrate into the concrete for a solid bond. It can also bond to previously painted or sealed concrete surfaces with little or no prep work.
A gallon will cover between 300 and 400 square feet and hide cracks and chips well, plus it seals and protects the concrete too. It is touch dry in 35 minutes and ready for a second coat or latex or oil topcoat in 60 minutes. The primer dries to create a bright white flat matte finish.
Best Concrete Sealer
Sealers come in clear or colored, dry-look or wet-look, glossy or non-glossy and help protect concrete from moisture, dirt, tire treads, grease, oil, and chemicals. Some sealers penetrate for more invisible protection, and others leave a durable, smooth film-like coating. A quality sealer will last from 3 to 10 years or longer depending on environmental exposure and use, so expect reapplication to become part of the maintenance protection plan.
Our top pick is SILOXA-TEK 8500 concrete and masonry penetrating sealer. The low-VOC water-based sealer repels water, oil, and salt, and is resistant to mildew, mold, fading, and efflorescence.
The sealer helps prevent cracking and surface erosion, increasing the life of your finish. It penetrates quickly, is easy to apply, and won’t change the color of the concrete. The 8500 is ideal for winter conditions, rainy climates, and full sun exposure areas.
Siloxa-Tek 8500 is manufactured using quality silanes and siloxanes and has a 40% solids content. The DOT-approved sealer can be applied by brush, roller, or sprayer, and uses nanotechnology to penetrate deep into the concrete for longer-lasting protection.
It also allows the concrete to breathe and moisture to escape. Each gallon covers approximately 250 square feet, and two coats are recommended for best results. However, the second coat can be applied before the first is fully dry, allowing the job to be completed more quickly.
Conclusion
Painting concrete requires some prep work. The first step is figuring out if it has been sealed, and what type of sealer was used. If the concrete wasn’t sealed, or a paint-accepting water-based sealer was used, clean and wash the surface. Let it dry and apply a coat or two of an appropriate primer and a couple of coats of paint.
If the sealer used isn’t paint accepting, it may be stripped off, and/or the surface roughened to provide grip for primer and paint. The roughened surface also needs to be cleaned prior to applying primer and paint. Hopefully, you found this guide helpful and are better prepared to tackle your concrete painting project.
Eugene has been a DIY enthusiast for most of his life and loves being creative while inspiring creativity in others. He is passionately interested in home improvement, renovation and woodworking.