How To Apply a Concrete Sealer

Concrete Sealer Application Tools

There isn’t just one way to apply a concrete sealer. In fact, there are several ways in which a concrete sealer can be applied, and the best way to apply the sealer will depend on several factors. It is always best to follow the manufacturer’s directions, but here are a few things to keep in mind when applying a concrete sealer.

Here are a few application guidelines to follow with all concrete sealers:

  1. Check the manufacturer instructions and apply the sealer in accordance with their guildelines.
  2. Apply the concrete sealer to a clean and dry surface. Surfaces should be allowed to dry for at least 24 hours before applying a sealer, and kept dry for 24 hours after applying the sealer.
  3. When applying a concrete sealer to exterior concrete, apply the sealer in the later afternoon or early evening. During this time, all dew has had a chance to evaporate and the concrete has had time to cool from exposure to UV rays. If you apply a concrete sealer in the middle of the day, you chance having the sealer evaporate, bubble, or delaminate.
  4. Penetrating sealers should be applied with a high volume low pressure pump sprayer, and acrylic sealers should be applied with a high volume low pressure pump sprayer or 3/8-1/2″ roller.
  5. If you are applying a concrete sealer to previously sealed concrete, make sure that either all of the old sealer has been removed or that the new sealer is compatable with the old sealer.
  6. If a concrete cleaner was used, make sure that all the cleaner has been removed. Some cleaners leave behind a surface residue, and others can change the PH of the concrete. Make sure the cleaner is removed, and if necessary, the concrete neutralized.

Tools Need to Apply a Concrete Sealer

There are a few different tools that will be required when applying a concrete sealer:

  • Pressure Washer: If you will be using a pressure washer to clean the concrete, you will need to rent a pressure washer.
  • Cleaner: You want to spot treat stains to allow for proper penetration. Oil, gas, and grease stains should be removed from the concrete.
  • Roller or Sprayer: You will need a 3/8-1/2″ shedless nap roller or a high volume low pressure pump sprayer. If you are applying a solvent based sealer with a pump sprayer, make sure the nozzle is solvent or acid resistant. If you are using a roller you will also need a roller pan.
  • Gloves: Gloves should always be used to protect your skin.
  • Mask or Respirator: Masks or respirators should be used so that material is not inhaled during application.
  • 5 gallon pail: You will need a 5 gallon pail of the sealer being used requires mixing. Typically this is only required with concentrated silicates, or acrylic sealers being applied in a color.

How to Apply a Concrete Densifier Sealer

Concrete densifiers are sealers that increase the strength and density of the concrete. The two most popular types of densifiers are sodium silicate sealers and lithium silicate sealers.

  • Sodium silicate concrete sealers have a larger molecule and are designed for porous substrates. They are slower reacting silicates than lithium silicates and typically require that the surface is constantly flushed with water to prevent CSH formation on the surface. Lithium silicate sealers are fast acting silicates and are designed for dense concrete surfaces. Typically, the surface does not need to be flushed with water when applying a lithium silicate.
  • Concrete densifiers can be applied with a roller or sprayer, but a sprayer will allow for more consistent coverage, and also for better penetration. Two coats are required, but in some cases, three or more coats can be applied to achieve a desired level of hardness.
  • Concrete densifiers should be applied to unsealed concrete surfaces. They can’t be applied to concrete that has been previously sealed, and can’t be applied over existing surfaces. They need to penetrate directly into the unsealed surface so that they can chemically react with the free lime and calcium below the surface.

Concrete densifiers are available in two forms, concentrated and pre-diluted. Concentrated densifiers allow the applicator to dilute their own sealers while pre-diluted sealers come ready to apply. There are many benefits to purchasing a concentrated silicate. First, concentrated silicates are more cost effective. You only pay for material and shipping costs are dramatically reduces. Second, concentrated silicates allow the applicator to apply the sealer at their desired level of concentration. Concentrated silicates will come with a suggested dilution ratio, but the ration can be adjusted to account for porous and wet concrete.

Lithium Silicate Concrete Sealers:

Sodium Silicate Concrete Sealers:

How to Apply a Water Repellent Concrete Sealer

Water repellent sealers are designed to repel surface water and liquids, and reduce deterioration caused by water absorption. They also help to reduce the growth of mold and mildew, and the formation of efflorescence.

Water repellent sealers are fairly straight forward. Whether you are applying a Silane sealer, Siloxane sealer, Silane-Siloxane sealer, or Siliconate sealer, the application process is fairly similar.

First, make sure the surface is clean and dry. If you used a pressure washer to clean the concrete, make sure the concrete has had at least 24 hours to dry.

Next, get ready to apply the sealer. Water repellent sealers can be applied with a roller or sprayer, but a sprayer will allow for more consistent coverage, and also for better penetration. Most water repellent sealers require two coats. Water based water repellent sealers need the two coats to be applied back-to-back before the sealer has had a chance to dry, but solvent based water repellent sealers can space the applications out.

Water repellents can be used to reseal concrete, but there are a few guidelines to follow:

  • Water repellent sealers can be applied over concrete previously sealed with a concrete densifier so long as it has been at least 7 days since the densifier was applied.
  • Water repellent sealers can be applied over concrete previously sealed with a water repellent sealer so long as the old water repellent has worn off or been completely removed.
  • Water repellent sealers can’t be applied over an acrylic sealer or concrete coating. They need to penetrate through the surface in order to chemically react.

Water Repellent Concrete Sealers:

How to Apply an Acrylic Concrete Sealer

Acrylic concrete sealers are fairly easy to apply, but water and solvent based acrylic sealers have a few differences.

  • Make sure the concrete is clean and dry, dry being the most important factor. If water was used to clean the surface, or if it rained, it is important to let the surface dry for at least 24-36 hours. After the acrylic sealer is applied, it is also important to keep the surface dry for at least 24-36 hours.
  • Apply the acrylic sealer in the late afternoon or early evening. During the time, the surface will be the most dry and the surface will have had a chance to cool down from exposure to the UV rays. If the acrylic is applied to hot concrete, you chance the water or solvent evaporating before the sealer has had a chance to cure, and you chance solvent bubbles and blisters from forming.
  • If you are applying a water based acrylic sealer, it is important to stay within the recoat window. If you are applying a solvent based acrylic sealer, consider spacing the second coat out 12-24 hours. This will give the first coat time to cure and prevent the second coat from being soaked up into the concrete. This will result in a better level of gloss and a stronger surface coating.
  • Acrylic sealers can be applied with a roller or sprayer when applying the sealer in clear. If you are applying a colored acrylic sealer, or are applying an acrylic sealer with a non slip additive, consider a roller instead. Sprayers can’t mix product as the product is being applied. Using a sprayer can cause inconsistencies in color. Further, non-slip additives can cause the sprayer to jam, resulting in sprayer failure.

Best Acrylic Concrete Sealers: