Thompson’s Water Seal is a popular waterproofing sealer designed for exterior wood, concrete, and masonry surfaces like decks, fences, foundations, and driveways. But is it really worth the cost? Here’s what you need to know about Thompson’s Water Seal to decide if it’s the right product for your waterproofing project.
What is Thompson’s Water Seal?
Thompson’s Water Seal is a penetrating waterproofing sealer made by Thompson’s Company. It is designed to protect exterior surfaces like wood, concrete, stucco, brick, and stone from water damage. Thompson’s Water Seal soaks deep into porous surfaces to form an invisible barrier that prevents water absorption while still allowing moisture vapor to escape.
The active ingredient in Thompson’s Water Seal is alkyd resin, a synthetic binding agent that cures into a water-resistant coating. In addition to the alkyd resin, Thompson’s Water Seal also contains paraffin wax, solvents like mineral spirits, and silica ingredients.
Thompson’s Water Seal is available in clear and tinted formulas in one gallon and five gallon sizes. The clear formula allows the natural color and texture of the surface to show through, while the tinted versions add a slight color tint. There are also several specialty formula options like Water Seal Plus Clear Wood Protector, Water Seal Plus Semi-Transparent Stain, and Water Seal Wet Look High Gloss Sealer.
What are the advantages of using Thompson’s Water Seal?
Here are some of the main benefits and advantages of using Thompson’s Water Seal:
- Provides long-lasting water protection – The manufacturer claims the coating lasts up to 10 years on decks and 5 years on fences, brick, and stucco when properly applied and maintained.
- Penetrates deep into porous surfaces – It soaks into the material instead of forming a surface film, which provides better protection.
- Allows surfaces to breathe – It repels liquid water but still allows moisture vapor to pass through, so condensation can escape.
- Won’t peel or flake – It bonds directly to the material for a more durable coating that won’t peel or flake off over time.
- Easy soap and water cleanup – Brushes and equipment can be cleaned up with just soap and water since it’s a water-based formula.
- Enhances wood tone – The waterproofer helps pop the natural color and texture of wood surfaces.
- Acts as a preservative – It protects wood from rot and decay caused by moisture damage.
What are the potential drawbacks?
While Thompson’s Water Seal does provide good water protection, there are a few potential disadvantages to consider:
- Requires reapplication every 1-5 years – It needs to be reapplied periodically to maintain effectiveness.
- Not ideal for immersion service – While it repels surface water, it won’t stand up to constant immersion or pooling.
- Color tints can be tricky – The tinted versions may end up darker than expected on the surface.
- Not for indoor use – It’s only intended for exterior surfaces.
- Not designed for non-porous surfaces – Won’t work well on metal, vinyl, or other non-porous materials.
- Won’t fill cracks – It only works on structurally sound materials without cracks or holes.
How does Thompson’s Water Seal compare to similar products?
Thompson’s Water Seal is comparable to other oil-based penetrating waterproofing sealers for exterior wood, concrete and masonry. Here’s how it stacks up against some similar products:
| Product | Active Ingredient | Price per Gallon | Advantages | Disadvantages |
|---|---|---|---|---|
| Thompson’s Water Seal | Alkyd resin | $25-$35 | – Good penetration – Allows surface to breathe – Easy soap and water cleanup |
– Requires frequent reapplication every 1-5 years – Not for immersion service |
| Behr Premium Waterproofing Sealant | Acrylic | $25-$30 | – Low odor – Soap and water cleanup – Can fill small cracks |
– Forms a surface film – May peel or flake over time |
| Rainguard Micro-Seal | Silane/siloxane | $70-$150 | – 10-year protection – Allows surface to breathe – Reduces efflorescence |
– Very expensive – Requires professional installation |
As you can see, Thompson’s Water Seal provides a good balance of penetration, breathability, and ease of use at a moderate price point compared to competitors.
How well does it work on different surfaces?
The performance of Thompson’s Water Seal can vary quite a bit depending on the type of material you use it on:
Wood
Thompson’s Water Seal works very well on exterior wood surfaces like decks, fences, siding, and outdoor furniture. The alkyd resins soak deep into the wood grain to repel water. It’s especially effective on more porous softwoods. Reapplication every 1-2 years is recommended for wood.
Concrete
Sealing concrete driveways, foundations, and walkways helps protect against freeze-thaw damage and spalling. Thompson’s Water Seal penetrates about 1/8″ into concrete and needs re-coating every 2-3 years for best results.
Stucco and Brick
On masonry surfaces like stucco and brick walls, Thompson’s Water Seal provides good water beading and protection against wind-driven rain and sprinklers. Reapply every 2-5 years on masonry.
Tile and Metal
Thompson’s Water Seal is not designed for non-porous surfaces like tile, vinyl, or metal siding. On these materials it will just form a surface film that is likely to peel.
How to apply Thompson’s Water Seal
It’s important to apply Thompson’s Water Seal correctly to get the advertised performance. Here are some application tips:
- Prepare the surface – Clean the surface of any dirt, mildew stains, loose paint or old sealers. Make repairs to cracks, nail holes, etc. Allow new concrete and masonry to cure 30 days.
- Add slip resistance – For decks and outdoor steps, add an anti-slip acrylic additive like Thompson’s Water Seal Non-Skid Pads for safety.
- Test absorption – Mist a small area with water. If it beads up, the surface is sealed and needs to be stripped. If it soaks in, it’s ready for the new sealer.
- Apply during ideal conditions – Apply when temps are between 50-90°F with low humidity and no rain forecast for 24-48 hours.
- Stir thoroughly – Mix the sealer well before and during application. Use a paint stick to reach the bottom.
- Use proper tools – Apply with a high quality brush, roller, or sprayer. A brush works best for rough surfaces.
- Apply liberally – Apply enough product so the surface stays wet for a few minutes before soaking in. Avoid drips and runs.
- Allow to penetrate – Let the first coat fully soak in for at least 24 hours before applying a second coat.
- Apply second coat – Two coats are recommended for optimal water repellency and longevity.
Does Thompson’s Water Seal require any special maintenance?
To keep surfaces protected by Thompson’s Water Seal looking their best for as long as possible:
- Reapply every 1-5 years depending on the surface type.
- Test water repellency annually. Reapply if water no longer beads up.
- Clean treated surfaces at least once per year with an all-purpose cleaner.
- Lightly sand and recoat worn or trafficked areas as needed.
- Remove mildew or algae growth with bleach or a specialty remover before resealing.
- Make any necessary structural repairs before reapplying.
With proper application and regular maintenance, Thompson’s Water Seal will provide excellent water protection for many years.
Is Thompson’s Water Seal environmentally friendly?
Thompson’s Water Seal contains solvents that can be harmful if swallowed or inhaled in large quantities. However, when used as directed outdoors, it poses minimal health or environmental risk. The alkyd resins are derived from plant oils, and it cleans up with soap and water. Overall, it’s considered moderately eco-friendly among comparable waterproofing products. Lower odor and VOC options are available for interior use.
Conclusion
For exterior wood, concrete, stucco, and masonry waterproofing projects, Thompson’s Water Seal is an effective and affordable sealer that provides good protection when properly applied. The penetrating alkyd formula resists moisture damage, won’t peel, and allows surfaces to breathe naturally. Thompson’s Water Seal is especially convenient since it is readily available at most hardware stores and cleans up with soap and water.
However, Thompson’s Water Seal does require reapplication every 1-5 years for optimal results, so it may not be the best choice for surfaces that are difficult to maintain. It also won’t stand up to constant water immersion. For more heavy duty waterproofing applications, a thicker film-forming or epoxy coating may be preferable.
Overall, Thompson’s Water Seal offers a cost-effective balance of water repellency and breathability for many common exterior maintenance projects. Just be sure to follow the application instructions closely, maintain the treated surfaces regularly, and reapply as needed to get the best performance.