Concrete sealer protects concrete from water damage and spills. But, to get good protection, you need enough coats of it. So, how many coats of it should you apply?
You should apply two coats of concrete sealer. The first coat serves as the undercoat or substrate to seal the surface. This coat will most likely disappear into the surface and you’ll need the second coat to provide the finish and cover the first coat.
It’s not recommended to apply more than 2 coats as the finish can develop bubbles and turn tacky.
Why Does it Matter?
The number of coats matters for concrete sealers because it determines the type of finish you’ll get and how well it will protect the surface from moisture It also determines how long it will take the sealer to dry and the color shade you’ll get when it’s dry.
More coats of the sealer equal more protection against moisture while fewer coats equal less protection. More coats also mean that the finish will take longer to dry since there’s more solvent to be evaporated.
If you are working with a tinted concrete sealer, the number of coats also determines the color shade you’ll get when the finish dries. They contain a color pack to give the sealer finish some color. More coats will give you more color than fewer coats.
For a transparent sealer, more coats mean that the finish will be less transparent and blurrier. On the other hand, fewer coats mean that the finish will be clearer and less blurry.
You Need a Second Coat if:
To know if you need a second coat, you should inspect the first coat after it has dried. Usually, the first coat is absorbed into the concrete surface after application. If this is the case, then you need to apply one more to provide better coverage.
If you are using a tinted concrete sealer and the first coat turns out lighter than you want, you should apply a second one to get a more colorful finish. You can check the user’s guide or manufacturer’s instructions for whatever concrete sealer you are using to know for sure if a second coat is recommended.
You can also try out the water test. For the water test, sprinkle some water directly on the finish when it has cured. Usually, this takes 24 hours.
If the water is absorbed into the finish, then you need another coat because the surface is still porous. However, if the water doesn’t absorb or affect the concrete in any way over a few hours, it means the one coat is perfect.
If You Apply Too Many Coats:
Applying too many coats will result in a blurry or whitish finish. Over time, the concrete sealer will detach from the surface and peel off gradually. When this happens, the surface will have no protection against moisture stains.
Concrete sealers are thick and sometime paste-like in texture. This means that each coat you apply is almost equivalent to two regular layers. This is why manufacturers recommend you apply only thin coats of it.
If you apply too many layers, it will result in the sealer being too thick. Thick layers won’t dry properly and can cause the finish to peel off because they trap moisture (solvent) between them.
The trapped moisture causes the sealer to swell gradually and allows air to get in. The presence of air and moisture in transparent sealers will make them turn whitish or blurry, while in tinted sealers, the colors will appear messy or wet.
Over time, the sealer will detach from the surface due to a lack of proper adhesion and will peel off. At this stage, the surface is no longer protected from water damage or discoloration.
If You Don’t Apply Enough Coats:
If you don’t apply enough coats, the sealer will not be waterproof when dry. Also, if you used a tinted sealer, you will not get enough color on the finish.
Usually, the first layer is absorbed in the surface. This is the substrate or undercoat that goes into the surface to seal it from the inside. It is usually unnoticeable since it penetrates the surface so you usually need at least a second coat for good sealing, coverage, and protection.
If you don’t apply enough coats, the sealer will not protect the surface from moisture completely and you won’t get a durable finish. It will also take little effort to dent it.
Dry Time Between Coats
It takes concrete sealer 2-6 hours to dry enough for a re-coat. However, the topical concrete sealer type often takes a few more hours to dry between coats.
To know exactly the dry time, check the user’s guide of the sealer that you are using. Manufacturers often indicate it in the user’s guide.
If you don’t have a user’s guide, you’ll need to keep tabs on the first coat to know when it is dry enough for a recoat. When you notice that the first sealer has been absorbed, you can apply a second coat.
Also, if the first coat is dry and hard, you can apply a second coat. However, the best way to get a perfect finish is to wait before applying the second coat. You can’t go wrong even if you wait more than 6 hours between coats. Just make sure to clean the coating before applying the next one.
During humid or cold temperatures, the dry time is extended because the evaporation rate of the solvent is slowed down. The longer it takes the solvent to evaporate from the coating, the longer the finish will remain wet.
In summary, 2 coats of concrete sealer are enough on any surface. You should always check and follow the manufacturer’s instructions when applying it so you don’t mess up the finish.
Also, always leave enough dry time between coats. If you aren’t sure how long to wait between coats, just wait 6 hours.
Tony is a professional painter and an author of DIY Geeks. Tony has completed over 1,000 painting projects for his clients. It's safe to say he knows what he Is talking about,