By definition, a water repellent sealer is a sealer that repels water. There are two primary categories of water repellent sealers. The first category is a penetrating water repellent sealer and the second is an acrylic sealer. I prefer to classify acrylic sealers as coatings because they leave behind a visible coating on the surface, but the industry refers to them as sealers so they will be discussed in this article as well.
Penetrating Water Repellent Sealers
First, let’s discuss penetrating water repellent sealers. Penetrating water repellent sealers chemically react within the surface to form a hydrophobic barrier within the pores. This barrier, which can not be seen from the surface, caused water and other liquids to bead off the surface. Typically the bead fades anywhere from six months to a year after applying, but the product continues to work for up to 7-10 years to reduce water absorption on the surface by up to 95%. Surfaces sealed with a penetrating water repellent sealer look dry even when wet, and dry significantly faster when exposed to large amounts of water. They help to reduce cracking, spalling, and pitting caused by water absorption, and they reduce the growth of mold, mildew, and efflorescence. Water repellents are great sealers to use on interior and exterior concrete, brick, paver, stone, and masonry surfaces.
There are several types of penetrating water repellent sealers, but the most common are:
- Silane sealers – Silane sealers have a smaller resin and work to protect concrete below the surface.
- Siloxane sealers – Siloxane sealers have a larger resin and work to protect concrete on the surface.
- Silane-Siloxane sealers – Silane-Siloxane hybrid sealers give you the best of both worlds. You get the below-surface benefits offered by the Silane sealer and the above-surface benefits offered by the Siloxane. This is the ideal sealer for virtually all types of concrete and masonry surfaces.
- Siliconate sealers – Siliconate sealers are very cost effective water repellents. Silane-Siloxane sealers take up to 72 hours before water beads off the surface but with Siliconates, water starts to bead almost immediately. Siliconate sealers should only be used on porous white and light gray concrete surfaces. They should not be used on trowel finished concrete, or on brick, pavers, stone, or masonry. When applied outside of these limitations, a white residue can form on the surface.
There are a few manufacturers that have posted videos on water beading off concrete. We think this video does a great job of visually showing how water repellents perform, and what unsealed vs sealed concrete looks like when it gets wet.
I would like to bring up the fact that concrete densifiers (sodium and lithium silicates) are not water repellent sealers. Densifiers are very different from water repellents. Densifiers chemically react to form a hardened crystalline barrier within the pores. The increase the strength and density of the concrete surface. If you dump water on a surface sealed with a densifier, the surface will absorb the water the same as it would if it were unsealed. Water repellents repel water. They force water to stay on the surface. Surfaces sealed with a water repellent sealer look dry, even when wet. If you want a densifier and a water repellent sealer, you need to apply a densifier first, and then apply a water repellent seven days later.
Best Penetrating Water Repellent Sealers
Not all water repellent sealers are the same, even if they fall under the same category. There are several factors that should be considered when choosing a water repellent sealer.
- Solids Content – This is directly associated with active materials – how much of the product is the actual chemical? Cheaper products sold in big box stores have a solids content of 2-8%, which means 92-98% of what you are buying is either water or solvent. More expensive, or premium products, have 20-40% solids. Premium products offer up to 10 times more active materials than cheaper products. While the difference may not be evident between the two on day 1, you will notice a clear difference by the end of year 2, 3, 4, and 5. This is one industry where better products will last longer and perform better. Featured products: Eagle Sealer (2-8% solids, average 3.8 star review), Armor SX5000 (40% solids, average 4.8 star review).
- Formula – Solids content is not the only part of the formula that matters. The second part of the equation is where the raw materials are sourced. Some manufacturers use imported and recycled resins in order to keep costs down, while other manufacturers use high quality US manufactured resins. How can you tell the difference? Most manufacturers that source US resins will proudly talk about it somewhere on their website while manufacturers that don’t, won’t mention anything about it.
- Customer Service – This is perhaps one of the most important things to consider when buying a sealer. The sealer can’t talk. If you have questions about the product or application, or issues during the time of installation, you will need access to information online, or to talk to a live person. Does the company give you access to information you need? Does the company have Live Chat? Are the customer service representatives helpful? Do they sound knowledgeable? Are they trying to sell you a product, or a solution? These are all important things to consider when making a purchase.
Penetrating Water Repellent Sealer Reviews
- Eagle Natural Seal (average 4.0 star review)
- Armor SX5000 Concrete Sealer Review (average 4.8 star review)
- Siloxane PD Concrete Sealer Review (average 4.5 star review)
- Okon S-20 Concrete Sealer Review (average 4.0 star review)
- Thompson’s Water Seal Concrete Sealer Review (average 3.2 star review)
Acrylic Water Repellent Sealers
Acrylic sealers are not classified as water repellents, but they do leave behind a coating that repels water. Acrylic sealers are great to use if you want to change the look or color of the concrete or pavers, and protect the surface against the damaging effects of water absorption, mold and mildew, and efflorescence. Acrylic sealers will aid in achieving a wet look, low gloss, or high gloss finish. They can also be tinted and applied in a color.
Now, it is important to mention that water repellent sealers, like Silane-Siloxanes, and coatings that protect against water, like acrylics, don’t offer many, if any, of the same benefits. Let me explain.
Acrylic sealers enhance the look of concrete and pavers with a protective film that protects the surface against water, staining, surface abrasion, mold and mildew, and de-icing salts. Acrylic sealers need to be resealed every 2-3 years in order to maintain a consistent finish. If the acrylic starts to break down and the concrete or pavers become visible, the exposed substrate will absorb water and therefore be susceptible to the damaging effects of water absorption. Acrylic sealers are also sensitive to sub-surface water and moisture. High amounts of moisture, especially during the time the acrylic is applied, can cause the acrylic to delaminate (turn white).
Penetrating water repellent sealers, like Silane-Siloxanes, last for up to 10 years and they are not sensitive to moisture. They need to be applied to dry concrete, but once full cured can actually help to reduce moisture by up to 2 lbs. Silane-Siloxane sealers are used alone as the primary sealer, and in many cases, before an acrylic sealer is put down to help extend the life of the acrylic. Some manufactures are starting to offer hybrid products, like the Armor AX25, that combines a water repellent sealer with an acrylic sealer.
Choosing the Best Water Repellent Sealer
You’ve learned about penetrating water repellent sealers, acrylic sealers, and hybrids – so which is the best water repellent sealer for your application? Well, only you can answer that. It comes down to what you are looking for in a sealer. For example:
- Do you want a wet look, low gloss, high gloss, or colored finish? If yes, you want an acrylic sealer.
- Do you want the concrete, brick, or pavers to look exactly as they did before being sealed? If yes, you want a Silane-Siloxane water repellent sealer.
If you are still unsure, it is best to talk to a concrete sealer manufacturer, a few of them. Explain your situation and what you are trying to achieve and let them suggest products. This will also help you to find the best company to buy from as you can get a feel for their technical knowledge and customer service.