Exterior wood surfaces such as decks and gazebos are exposed to harsh weather elements. If all the surfaces remain untreated, the elements can have a toll on your wood or deck boards and force you with frequent, costly repairs. 

Knowing how to apply Thompson’s water seal with a sprayer is one way to protect your exterior wood and save on repairs. 

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How to Apply Thompson’s Water Seal with Sprayer

To apply Thompson’s water seal with a sprayer, start by cleaning the surface with Thompson’s water seal heavy-duty deck stain cleaner. 

Let the cleaner soak the surface for 10 to 15 minutes. Then, go over it with a synthetic stiff-bristled brush and rinse with a garden hose. 

Let the wood dry for about three to four hours, and spray your Thompson’s waterproofing sealant on the entire deck. Once done, let the sealer dry for approximately 24 hours before putting it to use. 

That said, here is a detailed breakdown of the steps to follow and the supplies you need for this assignment. 

What you will need 

  • Thompson’s water seal
  • Garden sprayer/ airless sprayer for applying the sealer
  • Pinter’s tape and masking paper 
  • Microfiber cloth or rag for cleaning the surface
  • Water  
  • Drop cloth 
  • Synthetic stiff-bristled brush 
  • Paintbrush
  • Safety goggles 
  • Heavy-duty plastic gloves 
  • Long-sleeved clothing 

Thompson’s Water Seal Instructions 

Check to ensure you have everything you need within reach, then follow these steps to get the job done. 

Step 1: Clean the deck surface

Cleaning is one of those deck-maintenance projects that often fall through the cracks, so it is possible to find sticks, leaves, dog dander, or other debris lying around.

It’s essential to get rid of these things to clean your deck before waterproofing it. Whether you are sealing new wood or old, you must ensure no dirt or dust on the surface before applying the wet sealer.  

Apply Thompson’s water sealer heavy-duty deck cleaner for this part. The cleaner is versatile. 

It will do an excellent job removing molds, mildew, and residual clear and tinted waterproofing products on the wood—whether water-based or oil-based. 

It also cuts through accumulated layers of dirt, leaving the deck boards looking excellent and ready for waterproofing. 

How to clean the deck 

Start by wearing your protection; you need to have your rubber gloves and goggles on to protect your skin and eyes from the chemicals.

Apply deck stain cleaner on the surface and let it sit for 10 to 15 minutes. 

After the cleaner has soaked the wood for the recommended time, go over it with a synthetic stiff-bristled brush. 

Once you finish scrubbing the entire surface, rinse the boards with an airless paint sprayer and hose to remove the dirt and grime. Let the damp wood dry for three to four hours before proceeding to the next step. 

If you are working on something like a wood fence, you could use a damp microfiber cloth to clean it instead of a synthetic stiff-bristled brush. 

Step 2: Protect the adjacent lawn and objects  

Whether working on the deck or driveway, you want to protect the adjacent lawn from accidental staining. In addition, the chemicals you will be using can damage the lawn, so be sure to cover it with a drop cloth before getting started. 

You also need to cover any furniture nearby with plastic sheeting to avoid staining them. 

Consider covering the deck siding with painter’s tape and masking paper if the deck is connected to your home. 

Step 3: Prepare the sealer

You should get the best results with any Thompson’s water seal product. The sealant helps complement the color of your exterior space while letting you see the wood grain. 

You don’t have to wait for the wood to be dry before applying the waterproofing sealer. After rinsing, three to four hours is enough drying time, after which you can proceed with the next step.

Shake it inside its original container before pouring it into your preferred sprayer canister to prep your sealer. Close the sprayer canister and adjust the pressure as recommended by the manufacturer. 

If you are using a pump-up garden sprayer, you will need to pump the handle to pressurize. Ensure you stop pumping once you feel resistance, as indicated on the product label. 

Step 4: Spray it up

With your eye protection and gloves on, start spraying the product all over your deck, covering every inch with an even coat. 

Begin spraying by covering an approximately two feet-square section and follow it up with a medium nap paint roller. Next, roll over the covered section with a clean medium-nap roller to soak up any tiny puddles. 

Roll along the decking boards and across the boards, cleaning the roller between each use. Use a paint strainer in a rolling tray to clean the paint roller. 

Continue spraying and rolling until you have covered the entire surface. You could skip rolling if you are happy with the texture from spraying. However, you would have to test first on scrap wood to ascertain if you can achieve an even coat without rolling.  

Read: 1/2 vs 3/8 nap roller

Step 5: Allow the surface to dry thoroughly

After applying the water seal with a sprayer, let it dry for at least 24 hours before allowing any activity on the deck. 

The drying time may vary depending on the weather patterns. For example, your newly waterproofed fence or deck may take longer than 24 hours to dry if the weather is freezing. 

If your water seal doesn’t dry, quickly check here Why Thompson water seal is not drying.

Choosing a Sprayer for Water Sealer

The type or brand of the sprayer to use on this application is a personal choice. You should be able to work with any sprayer that gets the job done. For example, this can be a deck stain pump sprayer or garden pump sprayer with a hose. 

However, Thompson’s water seal manufacturer recommends using a plastic sprayer with a brass wand attachment when applying their products. 

So, while choosing a sprayer remains based on personal preference, you may keep this manufacturer’s recommendation in mind for better results. 

The important thing, though, is to clean your sprayer after every application. Run mineral spirits through the sprayer first, then follow up with clean water.

Recommended Reading: What is the best paint sprayer for furniture?

Best Sprayer for Thompson Water Seal Reviews

If you’re in a hurry, don’t worry. Here are Thompson’s water seal application sprayer reviews.

Best Sprayer for Thompson Water Seal

  1. Itisll Portable Garden Pump SprayerBest brass wand sprayer
  2. Vivosun 1.35 Pump Pressure SprayerBest for beginners
  3. Smith 190285 1-Gallon SprayerEasiest chemical sprayer to use
  4. Chapin 20000 Garden SprayerMost popular garden sprayer
  5. Deck & Home 190399 Universal SprayerBest for seals
  6. Chapin 20541 SprayerBest for large projects
  7. Scotts 190567 Lithium-Ion PumpBest battery-powered pump sprayer

1. Best brass wand sprayer – Itisll Portable Garden Pump Sprayer

Itisll Portable Garden Pump Sprayer Brass Wand Shoulder...
  • ★ Portable & Multi-Purpose Pressure Sprayer: This hand sprayer can be used for cleaning cars, irrigation plants, pet bathing, home cleaning. TIPS: This lawn sprayer is not suitable for corrosive or acidic solutions.
  • ★ Adjustable brass rod: The high-quality brass nozzle can adjust the intensity of the water spray from direct injection to fine mist spray. This sprayer is equipped with a comfortable 50-inch hose and extended 19-inch spray stick, which helps to spray longer distances or inaccessible places!
  • ★ Ergonomic handle: The ergonomic handle with locking trigger not only reduces fatigue, but also facilitates long-time spray operation. It can also be used to lock the trigger at the handle for continuous spraying with a steady amount of water. An adjustable shoulder strap makes it easy to hang the sprayer on your body for easy movement.

The first thing that catches your eye is the brass nozzle, which does a better job of producing a consistent spritz than plastic.

However, the manufacturer has gone even further by giving you two spraying options: water column spray or shower spray. This way, you can apply Thompson Water Seal on large projects that need a lot of pressure and even smaller ones like outdoor toys that need a gentler approach.

The portable garden pump sprayer has a long hose and a 19-inch spray stick to help you get to hard-to-reach areas like high fences or behind shrubs to make spraying even more comfortable.

The sprayer is also easier to operate as you need just one hand, plus it has a locking trigger for large projects. Itisll knew all of these features would go to waste if the pump was not easy to carry, which is why it comes with a shoulder strap.

When it comes to design, the body is made of high-quality polyethylene (PE), so you can see how much liquid is left as you work. It also comes with wear-resistant seals, rings, and anti-clogging filters to prolong the life of the product and to prevent uneven liquid dispersal.

To get the most out of this product, ensure you read the manual carefully, otherwise, the pump sprayer won’t work as expected.

What We Liked Most

  • Extra-long hose
  • Has a brass wand
  • Locking trigger for easy application
  • It comes with a shoulder strap

What Could Be Improved

  • It requires numerous refilling for large projects
  • The manual is in very small print

2. Best for beginners – Vivosun 1.35 Pump Pressure Sprayer

VIVOSUN 1.35-Gallon Pump Pressure Sprayer, Pressurized Lawn...
  • Adjustable Nozzle: This sprayer comes with water column spray and shower spray settings, you can adjust the tightness of the nozzle to achieve different patterns; 22.28-in long wand and 50-in hose increase spraying radius
  • Easy Operation and Safety: The ergonomic handle with locking trigger, you can drip or spray continuously by locking the handle or not; it has a safety valve setting that you can pull to release any built-up pressure
  • Easy to Fill and Check: The large bowl and funnel design on the top makes it easy to fill; This pressure sprayer uses a translucent bottle with a calibrated scale, so you can easily check the liquid level

Next, we have another highly practical garden sprayer. The Vivosun Compression Sprayer comes equipped with all the features you need for a multi-purpose applicator for indoor and outdoor use.

First is the sturdy design. The fire extinguisher-shaped body stays firm on the ground when applying Thompson’s Water Seal within a small area. The 22-inch wand gives you wide coverage from one spot.

However, if you prefer to carry the sprayer as you work, the Vivosun also comes with a shoulder strap for easy mobility. Another convenient feature is the trigger lock, so you’re not constantly squeezing the trigger.

You can also set the nozzle to shower spray, which is what you’ll need more often when applying Thompson’s waterseal, or water column spray, which is for hard-to-reach areas or stubborn patches.

The sprayer has a bowl-shaped mouth, which makes it easier to pour fluids in without it spilling. Even though the body is orange, it is translucent, so you can see what level the liquid is and top it up as needed.

To get the pressure to the desired level, you pump up and down a few times. Plus, there is a pressure release valve if you do it too often.

The only downside to this product is it has a plastic sprayer as opposed to brass, but the build quality is good, so this should serve you a long while.

What We Liked Most

  • Easy to carry
  • It has two spraying modes
  • It has a trigger lock option
  • Sturdy design

What Could Be Improved

  • Plastic wand is not long-lasting

3. Easiest chemical sprayer to use – Smith 190285 1-Gallon Sprayer

SMITH PERFORMANCE SPRAYERS 190285 1-Gallon Bleach and...
4,770 Reviews
SMITH PERFORMANCE SPRAYERS 190285 1-Gallon Bleach and...
  • Easy to use, 1-step assembly. Fill, pressurize and spray.
  • Use with bleach and other harsh chemicals when cleaning bricks, tubs, showers, siding, or even locker rooms
  • Shut-off has a comfortable grip and will lock on for continuous spraying

Next on our list is one of the easiest products to use. The D.B. Smith Bleach & Chem sprayer has a simple design, without any major bells and whistles. You can tell that it was designed for straightforward applications, making it perfect for applying Thompson’s Water Seal.

When you’re ready to use, this 1-gallon sprayer has a wide mouth, making it easier to fill with liquid. After that, all you have to do is pressurize the canister and start spraying. You can use this in a multitude of places, from decks to sidings, and it also has a locking trigger for continuous application.

One major design flaw is that it does not have a strap for easy carrying. However, the manufacturer has made up for that by providing a long hose – 36 inches. It also has an adjustable nozzle to change the pressure from mist to cone.

Despite being made of plastic, it has replaceable Viton seals and gaskets to make cleaning and maintenance easier, thus prolonging its lifespan.

While this pressure sprayer can be used to apply a range of products, it is not meant for stains or seals with high viscosity. Fortunately, Thompson’s Waterseal has low viscosity, so this product works great.

In the sea of positive reviews, some users have complained about the pressure. However, this will only be a problem if you try to apply the product on a windy day. Otherwise, it should work great.

What We Liked Most

  • Easy to apply
  • It has an adjustable nozzle
  • Long hose
  • It has a locking trigger

What Could Be Improved

  • The plastic wand is not very sturdy
  • The pressure can be weak

4. Most popular garden sprayer – Chapin 20000 Garden Sprayer

Next, we have the most popular garden sprayer on Amazon. While this can easily be attributed to its low price, the fact is the Chapin 20000 is an excellent product.

For starters, it is made of a solid, translucent polypropylene body. The wide mouth also makes it easier to fill and clean. Next, it has a decent 34-inch hose, which is longer than most. This will allow you to reach tough spots and spray over ornaments or shrubs.

The Chapin also comes with a 12-inch plastic wand and an adjustable cone nozzle that allows you to change from mist to column spray. Compared to other products on our list, one design limitation is that it does not have a locking trigger for continuous spraying. However, it does have an ergonomic handle that is easy to manipulate.

This garden sprayer also has an in-tank filter that allows you to continue spraying even when there is debris in the tank. Another benefit of the filter is that it ensures even spraying, which is essential when applying Thompson’s Water seal.

Even though this Thompson water seal sprayer is all plastic, it is remarkably durable. You can expect to own this product for years without it letting you down.

What We Liked Most

  • Rugged body that lasts for years
  • In-tank filter
  • Long hose and wand
  • Very affordable

What Could Be Improved

  • It does not have a trigger lock
  • It does not have a shoulder strap

5. Best for seals – Deck & Home 190399 Universal Sprayer

Deck the Home Deck & Home 190399 Universal Sprayer, 2 Gallon
  • 2 gallon sprayer for lawn and garden care, insect control and watering plants. Not designed to apply stains.
  • Premium shut-off with comfort grip and lockable shutoff for continuous spraying
  • Viton seals and gaskets throughout the pump and shut-off for long lasting chemical resistance

Unlike most of the other products on our list, this particular garden sprayer was built to apply products like Thompson’s Waterseal. While it can be used to spray pesticides, weedicides, bleach, and water, etc., it is also meant for low viscosity, water-based sealers, which is a first.

As a result, Deck & Home has made improvements to typical garden sprayers for this purpose. 

For starters, this is a 2-gallon tank, so it has been built for more continuous action. To support this function, this garden sprayer also has a premium shutoff function that allows you to spray continuously without squeezing the trigger.

According to the manufacturer, the Universal Sprayer requires 25% fewer pumps per gallon than their leading competitors. If true, this comes in handy when spraying large projects like a fence, as it will require fewer stops.

One other feature that separates it from its peers is that this sprayer comes with four nozzles. While this is not as convenient as an adjustable nozzle, each one delivers more consistent pressure.

The Deck & Home sprayer also has Viton seals throughout the pump and shutoff to improve safety and longevity.

Besides these fanciful yet practical extras are also the common ones such as a wide mouth for easy pouring and a pressure release valve.

What We Liked Most

  • It comes with 4 nozzles
  • Requires 25% fewer pumps
  • It has a continuous spraying shutoff
  • Ideal for large projects

What Could Be Improved

  • It does not have a strap
  • It does not have an adjustable nozzle

6. Best for large projects – Chapin 20541 Sprayer

Chapin International 20541 1 Gallon Lawn & Garden...
  • FOAMING NOZZLE: ideal for heavier coverage, you actually use less product because it foams and there’s more accuracy in chemical placement because you clearly see where it’s going
  • 1-GALLON POLY TANK AND NITRILE SEALS: translucent poly tank allows you to see fluid levels in tank, rust-resistant; nitrile seals are compatible with basic foaming lawn and pest control chemicals
  • MADE IN THE USA WITH GLOBAL MATERIALS: designed and produced in the USA with US-based customer service and technical support, located at Chapin’s home base in Batavia, NY; backed by Chapin’s 1-year limited warranty

If you’re thinking Chapin thought this product was so nice they named it twice, you are right on the money! Well, sort of!

The Chapin 20541 is a minor upgrade to the Chapin 20000. It has most of the same features that made us love its baby brother.

For starters, this is available as a 1-gallon, 2-gallon, or 3-gallon tank, each one delivering exactly the same performance. Depending on how much Thompson’s waterseal you need to apply, you can choose the appropriate size. Of course, the bigger it is, the more expensive it is.

Next, this is still a translucent bottle that makes it easier to tell when to refill, which is still easy thanks to the wide mouth. You also get the in-tank, anti-clog filter that saves you time and protects the lifespan of your sprayer.

Now, for the differences. The Chapin 20541 also has a 12-inch wand, but it comes with a 34-inch hose, which is 6 inches longer. It also comes with two nozzles instead of one. The standard nozzle is adjustable for fine or coarse spraying and a foaming nozzle for more precise application.

Unfortunately, this Thompson water seal sprayer still does not have a carrying strap or a continuous spraying button. Otherwise, this is still another excellent pump sprayer.

What We Liked Most

  • It comes with two nozzles
  • Has an in-tank, anti-clog filter
  • Solid build quality
  • Very affordable

What Could Be Improved

  • No carrying strap
  • No continuous spray function

7. Best battery-powered pump sprayer – Scotts 190567 Lithium-Ion Battery Powered Pump

Scotts 2 Gallon Lithium-Ion Battery Powered Sprayer with...
4,761 Reviews
Scotts 2 Gallon Lithium-Ion Battery Powered Sprayer with...
  • No more pumping.
  • Rechargeable lithium-ion power. Sprays up to 12 full tanks per charge.
  • Premium, commercial grade shut-off with comfortable grip; lock-on feature; and easy-to-clean, in-line filter

Finally, we come to the first and only battery-powered pump sprayer on our list. Also, this is the only product on our list made for professional sprayers. However, if this will be your first experience with a battery-powered option, then this will be perfect for you too.

Like all of the great garden sprayers mentioned above, this beauty has a sturdy base, a solid plastic body, and is easy to apply. It comes with a 21-inch poly wand with a 3-in-1 nozzle that can shoot fan spray, stream spray, or cone spray.

It also has an in-line filter, which will prevent debris from flowing out of the tank and onto your woodwork. The Viton seals in the shutoff, which has a lock-on feature, by the way, will protect the sprayer from chemical damage for much longer than typical sprayers.

In terms of safety, this also has a pressure release valve, similar to the other products on our list, but that is where the similarities end.

What sets this garden sprayer apart is you don’t need to pump it before spraying. The battery pack automatically builds the pressure, so all you have to do is aim and squeeze. You can spray up to 12 tanks before you need to recharge, which only takes about three hours.

The major downside is this sprayer is much heavier than the manual alternatives, and it is also a lot pricier. However, this will save you time during application, making it worth the extra for professional users.

What We Liked Most

  • It has a 3-in-1 nozzle
  • You don’t need to pump before spraying
  • The spraying pressure is consistent
  • Battery charges quickly

What Could Be Improved

  • It is quite heavy
  • It is pricier than most manual options

How to Tell if Your Deck Needs Waterproofing

To know when to seal your deck with Thompson’s water seal, look for the telltale signs indicating whether the wood is still protected or is porous and vulnerable to water damage. 

Look for discoloration on the edges and surface

For an old deck, first, examine the surface for discoloration. If there’re black spots that are not oily deck stains or dirt, they could be molds and mildew. 

If you see green patches, especially on the edges of the wood, those are algae. 

Both mildew and algae thrive where there’s dirt and moisture. Therefore, their presence is clue enough that your deck boards are absorbing moisture to sustain mildew and algae growth. 

Graying wood 

Nearly every untreated wood develops a grey patina over time. So if your deck boards are grey, that’s a sufficient clue that the wood is untreated and likely vulnerable to the elements.

Check out our guide on water-repellant sealer for pressure-treated wood deck.

Check for visible cracks on the wood

When wood absorbs water, it swells. When the water evaporates, the wood contracts. If this cycle of swelling and shrinking continues over time, it causes the wood to crack. 

Such wood can become weak and hazardous to your family. Waterproofing helps protect the wood from such structural damage. 

Wood absorbing water from a splash test

A more conclusive way to determine if your deck needs waterproofing is through a splash test. Sprinkle some water on various sections of the deck and observe what happens. 

If the wood absorbs the water and darkens within a few seconds, it is porous and requires waterproofing. However, if the water beads up on the wood surface, it’s still protected and doesn’t need waterproofing. 

Choosing Your Sealer 

Not all Thompson Water Seal products are created equal. They are available in different colors across various price ranges. So, you will want to consider your exterior décor and go for something that will sync with it. 

More importantly, you want a sealant that will offer the best protection for the longest time possible. 

Today, sealers are available in three distinct categories with varying properties that will affect the quality of protection you get from each. It is essential to understand the different characteristics to select the most appropriate deck sealer. 

Solid stain

This category of stains has the thickest consistency and can offer the ultimate protection for wood. It seals each deck board against water while protecting it from UV rays with its pigmented tint.

The UV protection means applying stain helps keep your wood from becoming discolored. 

Semi-transparent stain

Semi-transparent stains come in a variety of colors that offer significant UV protection in addition to waterproofing the surface. 

Given the colors and paint thinner (mineral oil) consistency, the semi-transparent stain lets you see the wood grain while modifying the appearance of your deck wood for the better. 

Clear sealer

As the name suggests, the clear sealer has no pigment. As such, it offers minimal protection against direct sunlight. If you waterproof wood with a clear sealer, the boards will retain their color while enjoying protection against water damage. 

Clear deck sealers are an excellent choice if you wish to maintain the color of your wood.

One thing to keep in mind when selecting a deck sealer is, the lighter the water sealant, the more often you will need to reapply it. 

For maximum protection, you may want to go for a stain sealer that protects your wood from moisture and too much exposure to the sun. 

General Rules for Applying Thompson’s Water Seal With Sprayer 

After spending money on the sealer and the other application materials, you want to get the most of your investment. This section offers some tips to ensure you make the most of your time and money spent on Thompson’s water seal. 

  • Apply the sealer on a calm, still day. Windy conditions can make it difficult to spray the deck properly.  
  • Plan your sealing project on a day when no rain is forecast for at least two days. This will ensure your newly stained surface isn’t rained on before it’s completely dry.
  • Ensure you apply the sealant when the ambient temperatures are at least fifty degrees Fahrenheit. Temperatures lower than this can prolong the product’s drying time.  
  • If the pigmented stain clogs the tip of your sprayer, unscrew the tip and plunge it in mineral spirits to unclog it. 

Interesting read: Can you use Thompson water seal over stained wood?


Can you spray Thompson’s water seal?

Yes, you can apply your Thompson’s water seal using a standard pump garden sprayer and achieve the desired results. This sprayer is best to use when applying sealers. A pump sprayer may not be recommended for solvent-based sealers since they tend to have more active chemicals and corrosive agents not suitable for garden sprayers. You may also fail to get the coverage you want through regular spray gear.

What kind of brush do you use for the Thompsons water seal?

If you are not using a sprayer, consider using synthetic bristle brushes or rollers when applying a water-based finish. Notice that some water-based finishes recommend against using a roller, preferring a paint pad instead as the best alternative.

For an oil-based finish, consider using a natural bristled brush or roller cover instead.  

How many coats of Thompson’s Water seal waterproofing stains do I need?

You need to apply only one coat when waterproofing with a Thompson water seal. However, you can add a second coat if you prefer more color. Ensure you apply the second coat within two hours before the first coat dries. 

Also, check out: Olympic Waterguard vs. Thompson Water Seal

It’s all about the Spray

If you follow this guide, you should find it easy to know how to apply Thompson’s water seal with a sprayer and achieve the best results.

Of all the ways to apply stain, sealers, or any protective coat, spraying is by far the easiest and fastest method. And so, these are the same metrics we looked for when researching the best sprayer for Thompson’s Water Seal.

And the winner is the Itsill Garden Pump Sprayer. It has everything you’d want in a manual sprayer, including a durable wand. Even though the Chapin 20000 is the most popular option, it does not have a locking trigger or a shoulder strap.

While we fancy Scotts 190567 Sprayer, the price and weight might be too much for the casual user.

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