Thompson’s WaterSeal is a widely available, budget-friendly product that is excellent at repelling water on outdoor surfaces like wood, brick, and concrete. However, it generally lacks long-term UV protection and durability compared to premium penetrating stains, requiring frequent reapplication.
Thompson’s Water Seal typically lasts 1 to 3 years on exterior wood surfaces before it needs to be reapplied. However, the exact lifespan varies based on the product tier and environmental conditions, often requiring maintenance every 1 to 2 years in heavy-traffic or high-sun areas.
Thompson’s WaterSeal is highly praised for being affordable, easy to apply, and excellent at repelling water on contact. However, professional reviewers note that it lacks long-term UV protection. Users often have to reapply it annually on high-traffic or exposed outdoor wood.
Best Waterproof Finish for Wood: Our Top 4 Winners
Water seal protects wood from water and sun damage. It acts like a barrier, keeping moisture out. Without a water seal, outdoor wood can fade, warp, or rot, and all other sorts of things can occur to your deck unfortunately. Thompson's Water Seal goes further.
For best results ensure the surface is as dry as possible. Apply 2 coats using brush, roller and sprayer. The second coat should be applied when the first coat has soaked in to the surface. For best results do not leave the first coat to dry for more than 1 hour before applying the second coat.
That said, it should never be used in marine applications, countertops, or woodworking projects that come into direct contact with food, like bowls or cutting boards.
Thompson's® WaterSeal® Clear Wood Sealer provides waterproofing protection for exterior wood surfaces. The clear sealer enhances and maintains the wood's natural color.
The best wood treatment to prevent rot depends on your project, but the top professional-grade choices are penetrating Borate treatments for above-ground use and Copper-based preservatives for wood in direct soil contact. Both penetrate the wood fibers to stop decay fungi and insects at the cellular level.
Spraying: speed and superior finish
It's fast and delivers that coveted smooth, even finish, free from brush marks. This makes it ideal for tackling intricate details on joinery, or when you're looking for a flawless, high-end look on larger surfaces like cabinet doors.
The best way to apply Thompson’s Water Seal is by using a paint pad applicator or a garden pump-up sprayer to ensure deep penetration. Thoroughly prep the surface, apply one single, thin, and even coat, avoid over-application, and let it cure for 24 hours without rain.
In light of that, we prefer sealing over coating. Sealing wood protects wood from moisture and brings out its natural beauty at the same time. Sealer also allows wood to age gracefully. So much so, that the aesthetic differences between sealing and coating are truly remarkable.
Yes. In addition to providing maximum strength waterproofing protection, Thompson's® WaterSeal® Fabric Seal also contains UV inhibitors in order to resist color fading caused by the sun.
The best time to seal a deck is in late spring (May–June) or early fall (September–October) when temperatures are consistently between 50∘F and 90∘F and there is no rain in the forecast for 48 hours. Mild weather allows the sealer to dry evenly without bubbling or cracking.
There's a risk of trapped moisture, which can induce mold growth and material failure. Some waterproofing methods limit flexibility post-application, potentially causing structural issues. Waterproofing can pose environmental concerns due to harmful chemicals and energy-intensive production.
The most durable wood finish depends on your project. Epoxy is the hardest and most waterproof for tabletops, 2K Conversion Varnish is the industry standard for commercial furniture, Polyurethane offers the best DIY balance of scratch resistance for heavy-use items, and Spar Varnish handles exterior weather.
The most affordable way to waterproof wood is by starting with a natural wood oil and following with a coat or two of outdoor paint. Though more budget friendly in the short term, you will need to redo this method more frequently, as it is not as long lasting as, say, a pricier, high-quality sealant.
Yes, you can stop wood rot once it starts, but only if you eliminate the moisture source and treat or remove the damaged wood. While already-rotted wood cannot be "healed," you can stop the spread by drying the area, treating with fungicides like boric acid, or using wood hardeners on solid wood, followed by replacing severely damaged sections.
Best Oil-Based
You should apply Thompson's Water Seal every 1 to 3 years, depending on your local climate, sun exposure, and foot traffic. Horizontal surfaces (like decks) usually require reapplication every 1 to 2 years, while vertical surfaces (like fences) can last up to 2 to 4 years.
Because of the coloring aspects of oil-based poly, woods with a light color should use water-based polyurethane. Darker woods will benefit from the patina formed with oil-based poly.
The most common chemical used to treat lumber used to be chromated copper arsenate, or CCA. In 2003, however, the Environmental Protection Agency restricted the use of CCA in residential settings due to health and environmental concerns about arsenic leaching out of the wood.
Motor oil repels water and deters insects, effectively slowing down rot in outdoor wood, such as fence posts or barns. However, it is an unregulated, environmentally hazardous practice. It never fully dries, leaches into the soil, emits a strong odor, and poses toxicity risks.
Nowadays, CCA is a restricted chemical product in most countries, since potential environmental and health risks were reported due to dermal contact with CCA residues from treated structures and the surrounding soil, as well as the contamination of soils.