polyurethane over thomsons water seal

Read This Before You Put Polyurethane Over Thompson’s Water Seal

Thompson Water Seal is a popular sealant for decks and patios, but can you put polyurethane over it? 

There is a lot of conflicting information on whether or not you can put polyurethane over Thompson Water Seal. 

This discussion will explore the pros and cons of doing so and help you make the best decision for your home.

What is Thompson Water Seal, and what does it do?

Thompson Water Seal is a clear waterproofing sealant designed to protect porous surfaces from damage caused by water. The sealant forms a barrier that repels water and helps to prevent staining, mildew, and mold growth.

It can be used on various surfaces, including wood, concrete, brick, and stone. Thompson Water Seal is easy to apply and dries quickly, making it a popular choice for home and commercial use. When appropriately applied, it will provide long-lasting protection against the elements.

Can you put polyurethane over Thompson Water Seal?

Applying a sealant to your deck is essential for protecting it from the elements and ensuring its longevity. But with so many different products on the market, it can take time to know which suits your needs.

One common question is whether you can put polyurethane over Thompson Water Seal. The answer depends on the type of Thompson Water Seal you are using. The answer is yes if you are using the original Thompson Water Seal.

However, if you use the newer Thompsons WaterSeal Advanced Wood Protector, the answer is no. The Advanced Wood Protector contains a water repellent that will prevent polyurethane from adhering correctly.

So if you want to apply polyurethane to your deck, check the label first to ensure you are using the right product.

What can I put over Thompson’s water seal?

Many people enjoy the look of natural wood, but they want to avoid dealing with the hassle of maintaining it. Thompson’s Water Seal is a clear sealer that can be applied to any type of wood, including outdoor furniture and decks. It creates a protective barrier against water damage, making it ideal for areas exposed to the elements.

However, some people find that the water-repellent properties of the sealer can make it difficult to clean. In addition, it can change the color of the wood over time. If you’re looking for an alternative to Thompson’s Water Seal, there are several other options on the market.

Some sealers are designed to be more durable, while others offer better UV protection. You can also find sealers specifically made for outdoor furniture or decks. With so many choices available, you can find one perfect for your needs.

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How long will Thompson Water Seal last

Thompson Water Seal is a waterproofing agent that can be applied to various surfaces, including wood, concrete, and stone. It is typically available in a clear or tinted formula and can be applied with a brush, roller, or sprayer. When appropriately applied, Thompson Water Seal will last up to 4-5 years.

However, the specific lifespan of the sealant will vary depending on the type of surface it is applied to, the climate conditions in the area, and the amount of exposure to sunlight and water.

For best results, it is essential to follow the manufacturer’s instructions carefully and to reapply the sealant as needed to maintain its efficacy. However, with proper care and maintenance, Thompson Water Seal can help protect surfaces from water damage for many years.

What are the benefits of using polyurethane over Thompson Water Seal?

Polyurethane is a type of clear varnish that dries to a hard, durable finish. It can be used on wood, metal, and concrete surfaces and provides superior protection against scratches, stains, and water damage.

Thompson Water Seal is a sealant applied to porous surfaces to prevent water absorption. It is typically used on pavers, bricks, and stone. While Thompson Water Seal does provide some protection against water damage, it is not as durable as polyurethane and will need to be reapplied more frequently.

Polyurethane is also easier to apply than Thompson Water Seal and dries to a clear finish that will not change the appearance of the surface. For these reasons, polyurethane is the better choice for protecting surfaces from water damage.

Comparing Thompson’s Water Seal and Polyurethane

You have two main choices when protecting your wood surfaces: Thompson’s Water Seal and polyurethane. Both products effectively preserve the wood from water damage but have some key differences. Here’s a look at the pros and cons of each product to help you decide which is suitable for your needs.

Thompson’s Water Seal

Thompson’s Water Seal is a water-based sealer penetrates the wood to provide long-lasting protection. It’s ideal for surfaces exposed to harsh weather conditions or wears and tear.


  • Penetrates deep into the wood to provide lasting protection 
  • Won’t change the color of the wood 
  • Easy to apply 
  • Dries quickly 


  • It can be difficult to remove if you change your mind about the finish 
  • Not as durable as polyurethane 


Polyurethane is a synthetic resin that forms a hard, durable protective coating on the surface of the wood. It’s available in both oil-based and water-based formulas.


  • Provides a tough, durable finish that can withstand a lot of wear and tear 
  • Resists fading, yellowing, and chipping 
  • Easy to apply 


  • Takes longer to dry than Thompson’s Water Seal 
  • Can yellow over time 
  • Requires special ventilation when applying due to solid fumes

So, which one should you choose? If you’re looking for a quick, easy way to protect your wood surfaces that won’t change their appearance, go with Thompson’s Water Seal.

If you need a more durable finish that will resist wear and tear, go with polyurethane. And if you need help determining which is suitable, ask a knowledgeable salesperson at your local hardware store for advice.

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How to apply polyurethane over Thompson Water Seal

Applying a polyurethane topcoat to seal and protect your deck is essential, but it’s critical to ensure that the underlying sealer is fully cured before proceeding.

Thompson Water Seal is a waterproofing sealer penetrates deeply into the wood’s pores, providing long-lasting protection against moisture and ultraviolet rays. However, the sealer can take up to 30 days to cure completely.

If you apply polyurethane over an uncured coat of sealer, the two products may not adhere properly, leading to peeling and flaking. To be safe, wait 30 days after applying Thompson Water Seal before proceeding with a polyurethane topcoat.

Once the sealer is fully cured, you can apply polyurethane according to the manufacturer’s instructions. By ensuring that each layer is adequately cured, you can help create a lasting barrier against the elements and keep your deck looking great for years to come.

Tips for keeping your home protected with Thompson Water Seal and polyurethane

The best way to protect your home from the elements is to keep it well-sealed. That means using products like Thompson Water Seal and polyurethane to create a barrier against water, wind, and sun damage. But how do you know which product to use and when? Here are a few tips:

Start with a clean surface. Ensure you wash away any dirt, pollen, or other debris before applying any sealant.

Choose the right product. Thompson Water Seal protects wood surfaces from water damage, while polyurethane works well on wood and concrete.

Apply the sealant evenly. Use a brush or roller to apply a thin layer of glue over the entire surface. Follow the manufacturer’s directions for drying time and re-coat frequency.

Following these simple tips can help keep your home in tip-top shape for years to come.

Thompson Water Seal is a sealant used on various surfaces in and around the home to protect them from water damage.

Thompson Water Seal typically lasts 10 years, but adding a coat of polyurethane will increase its lifespan.

There are many benefits to using polyurethane over Thompson Water Seal, including increased durability, shine, and protection against UV rays. Polyurethane can also be applied over other sealants without causing any damage.

To apply polyurethane over Thompson Water Seal, clean the surface with denatured alcohol and allow it to dry completely before applying it. Make sure to follow all instructions on the product label for the best results.

You can keep your home protected from water damage by using Thompson Water Seal and polyurethane together. Be sure to regularly check all surfaces treated for leaks or water damage and repair them as soon as possible.

Apply Polyurethane Wood Finish

Can you put polyurethane over the wood sealer?

You should use a sealer before applying polyurethane if the wood is unfinished, unsealed, or has a sealer that is not compatible with polyurethane.

Can you polyurethane over the water seal?

Yes, you can use polyurethane over a water seal, but you should buff and clean the old finish properly before applying the new one.

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