Before applying a concrete sealer, the surface must be free of all mold and mildew. Below are a few processes on how to remove mold and mildew from concrete. We recommend using a facemask and rubber gloves in order to avoid inhaling the mold and mildew.

What is mold?

Mold is a type of fungus. The small organisms can be black, white, orange, green, or purple and live almost anywhere indoors and outside. Mold thrives on moisture and reproduces through lightweight spores that travel through the air. You’re exposed to mold every day. They’re usually harmless in small amounts. But when they land on a damp spot in your home (like concrete), they can start to grow. They release spores that you might breathe in. If you're sensitive to mold and inhale a lot of spores, it could make you sick.

Source: WebMD

How to remove mold and mildew from concrete

The first method is to use household bleach. Mix one cup of bleach to 1 gallon of water. It can then be sprayed onto the concrete and scrubbed. Most of the mold should be removed through this method.


A less aggressive method is to mix 1 cup of vinegar with 2/3 cups of water in a spray bottle. In order to treat a larger surface double, triple, or quadruple the ratio and use a low pressure sprayer. Spray the mixture directly on the mold and mildew and wait 30 minutes. After 30 minutes, spray more and scrub gently with a sponge. You should begin to see the mold and mildew scrub off. If there is still additional mold and mildew, spray with the vinegar/water mixture and wait another 30 minutes before scrubbing and wiping away the mold and mildew.

Once the mold and mildew has been reomved from the concrete if there are any grease stains, use the Micro-Degreaser 1100 to remove them.

If you are looking to etch the concrete after removing the mold and mildew use the Hydro-Etch 1000, an acid based concrete etcher or Eco-Etch 1001, a non-acid, eco-friendly based concrete cleaner.

After the mold and mildew has been removed you will want to use a penetrating concrete sealer to prevent it from growing back. By using a penetrating concrete sealer like the Siloxa-Tek 8500 mold, mildew and organic growth will be reduced and made easier to clean. The Siloxa-Tek 8500 is our favorite product to treat nearly any application. A proprietary blend of silane/siloxanes, this clear penetrating sealer not only prevents deicing salt and freeze-thaw damage, but its hydrophobic nature resists moisture intrusion and vapor transmission. This is the go to choice to seal any concrete, brick, or masonry based substrate especially driveways, basements, patios and garages exposed to mold and mildew.

Why Ghostshield?

With the molecular nanotechnology in Ghostshield concrete sealers, these unique formulations are unlike any other sealers on the market. Deconstructed and rebuilt one nanoparticle at a time, attention to detail and superior technological advances have made the sealers indestructible and specially engineered for the specific application of resisting the growth of mold and mildew. The Siloxa-Tek 8500 is the only concrete sealer you should be considering if you want indefinite, industrial grade protection from mold and mildew.

8500 Concrete Sealer Bottle

Siloxa-Tek 8500

Water & Salt Repel

Published Wednesday 15th of May 2024 // Updated Thursday 18th of March 2021

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