How to Apply Thompson Water Sealer? (Sprayer or Roller)

Many DIYers and homeowners find it tricky to apply Thompson’s water sealer and some don’t even know what applicator to use. Here is all you need to know about applying the water sealer.

To apply Thompson’s water, sealer, you need to first wipe and clean the surface. If you are working on a deck or exterior wood surface, you are to wipe down the wood with deck stain cleaner. Then scuff the wood, remove dust and apply two thin coats of the Thompson’s water sealer within 24 hours.

You can apply the Thompson water sealer using a paintbrush, roller, or paint sprayer. It’s important to allow the water sealer to dry for at least 48 hours before resuming normal use on the surface.

Keep reading this post to discover more about applying Thompson’s water sealer including the right paintbrush, roller, and paint sprayer to use. Let’s dive in.

Spraying vs Roller (For Thompson Water Sealer)

Spraying vs Roller (For Thompson Water Sealer)

When it comes to applying Thompson water sealer, two usual methods that painters use are spraying and using a roller.

Spraying involves the use of different types of paint sprayers and spray guns while rolling involves the use of paint rollers. So, which of these methods is the best? Well, to know which applicator method is better, we’ll have to review and compare both methods in-depth.


Spraying Thompson water sealer is one of the methods you can use to apply the water seal. This involves the use of HVLP paint sprayers or spray guns to expel a fine mist of the water sealer on the prepped surface.

Paint sprayers apply the water sealer in thin and light coats which makes the Thompson water sealer dry faster. Paint sprayers also apply plenty of water sealer in a short period which gives you good coverage on the surface. A quick dry time and good coverage mean that you can finish sealing the surface quickly.

However, paint sprayers need enough experience before you can use them flawlessly. This is because there is a lot that goes into using a paint sprayer from loading up the Thompson water seal to assembling your tools and priming the paint sprayer. If you don’t have any prior experience with a paint sprayer, you may find it difficult to apply the water sealer perfectly.

Pros of Spraying Thompson Water Sealer

  1. Spraying Thompson water seal gives good coverage on the surface.
  2. Spraying Thompson water seal allows the sealer coats to dry in time.
  3. Sprayers allow you to recoat sooner.
  4. In the hands of a professional, spraying Thompson water sealer gives the smoothest coat.
  5. Paint sprayers allow you to seal tight corners and crevices.
  6. Paint sprayers give more sealing as the water sealer is absorbed fully on the top layer of the wood.
  7. Paint sprayers are perfect for all surfaces regardless of how smooth or rough.

Cons of Spraying Thompson Water Sealer

  1. Spraying Thompson water sealer requires experience and skill.
  2. Spraying Thompson water seal involves a lot of prep work since you need to mask the surface, assemble the tools, and prime the spray gun before application.
  3. Once you have started spraying, you can’t take long breaks or pause the application because the water seal inside the paint sprayer will clog up the nozzle.
  4. It’s easier to over-apply the water sealer especially if you take too long spraying a spot.

Using A Roller

You can also apply your Thompson water sealer using a microfiber paint roller. Paint rollers offer good coverage on the surface because you get to cover more area with the roller. Rollers give easy application and you can overlap spots easily without worrying about streaks or brush marks.

Paint rollers aren’t designed to make the water seal dry fast. Though you get good coverage, you need to wait a bit longer for each coat to dry because rollers often apply Thompson water seal in thicker coats.

Pros of Using A Roller For Thompson Water Sealer

  1. Rollers give good coverage.
  2. You can overlap and recoat the Thompson water sealer quickly.
  3. Paint rollers can be used by beginners.
  4. Rolling Thompson water sealer doesn’t require much prep work as long as the surface is smooth.
  5. Rolling Thompson water seal is a cheap applicator method.

Cons of Using A Roller For Thompson Water Sealer

  1. Rollers apply thicker coats of Thompson water sealer.
  2. Rolling Thompson water sealer means that the seal will take a bit longer to dry.
  3. Rolling Thompson sealer can cause bubbles in the finish.
  4. Rollers only work on smooth and flat surfaces.

So, should you spray or roll on the Thompson water sealer?

Well, either you use a roller or paint sprayer to apply Thompson water sealer depends on you and the surface you are working on.

If the surface is rough or has lots of corners and ridges, it’s best to use a paint sprayer as sprayers can reach tight spots. Rollers are ideal for smooth surfaces. Also, if you want thin coats, you should use a paint sprayer as rollers apply thicker coats than paint sprayers.

Do You Have To Mix Thompson’s Water Seal With Water Or A Solvent Before Applying?

You don’t have to mix Thompson water sealer before application. Thompson water seal manufacturers advise against mixing, thinning, or diluting the sealer with any other type of solvent.

If you mix the Thompson water seal, the sealing properties of the coat would be reduced. What this means is that the water seal would not be as waterproof as it should be since you have mixed it with a foreign substance. Asides from this, the Thompson water sealer will not dry in time and can eventually turn tacky.

If you think the sealer coat is too thick for you and you want a thinner coat, it’s best to apply the sealer using a paint sprayer since paint sprayers apply light coats. Next, let’s find out how to apply Thompson water sealer with a paint sprayer easily.

How To Spray Thompson Water Sealer?

How To Spray Thompson Water Sealer?

Spraying Thompson water sealer is an easy task as long as you follow the right steps and use the right tools and attachments. Luckily, this post reveals the right steps to follow and the tools and supplies needed to spray the Thompson water sealer perfectly.

To spray Thompson water sealer, you’ll need the following tools and supplies:

  • An airless or a high-volume, low-pressure paint sprayer
  • A plastic or brass nozzle or extension
  • Masking tape
  • Paintbrushes
  • Clean rags
  • Mineral spirits or acetone
  • A pair of gloves
  • A paint shield
  • A pair of scissors
  • Water
  • A vacuum or duster
  • A face mask (for breathing protection)

Here is a guide on how to apply Thompson water sealer using an airless or HVLP paint sprayer:

  1. Put on a pair of gloves and breathing protection.
  2. Remove any existing sealer coat on the wood.
  3. Vacuum the surface that you want to seal to remove dust and debris on the surface.
  4. Wipe and clean the wood surface with rags and mineral spirits to remove grease and oils on the wood. If you are working on a deck, you can purchase the Thompson deck cleaner.
  5. Allow the wood to dry fully for 24 hours.
  6. Sand down the wood with 220-grit sandpaper and remove dust.
  7. Tape the areas of the wood that you don’t want to seal with masking tape. Surrounding objects and the floor should also be covered with sheets and masking tape.
  8. Prep the Thompson water sealer – follow the manufacturer’s instructions on how to do this. Usually, you only need to shake or stir the water sealer and it’s ready to be used.
  9. Assemble the paint sprayer – follow the user’s guide on how to do this.
  10. Load the Thompson water sealer in the cup of the spray gun – if the sprayer has a suction hose, put the hose into the Thompson sealer and put the return hose in an empty bucket.
  11. Prime the paint sprayer – to do this, switch the control knob to prime and ensure that the sealer comes out of the nozzle.
  12. Test the spray on a part of the wood to see if the sealer sprays well.
  13. Spray directly on the prepped wood – 2-3 coats of Thompson water seal are enough.
  14. Allow the Thompson water sealer to dry – this takes about 4 – 24 hours.
  15. Dissolve and clean the paint sprayer with mineral spirits or acetone. If you don’t do this, the sealer in the sprayer will dry up and clog the nozzle.

Tip: When spraying the sealer, keep the nozzle 10-12 inches from the surface so the sealer doesn’t ricochet on your face or body. Also, use a paint shield while spraying to prevent overspray.

Next, let’s check out how to brush on and roll on the Thompson water sealer.

How To Roll Or Brush Thompson Water Sealer?

How To Roll Or Brush Thompson Water Sealer?

If you don’t want to spray the Thompson water sealer on the surface, you can use a paintbrush or paint roller. Both applicator methods work as well as a sprayer when used correctly. So, let’s check out how to use both applicator methods correctly.

If you want to use a paintbrush, you’ll need a 4-inch paintbrush to apply the water seal. If you want to use a roller, you need a microfiber paint roller. You can also use a short and synthetic bristled paintbrush but this requires more skill and experience.

Here is a guide on how to roll or brush Thompson water sealer:

1. Do A Splash Test

The first step is to do a splash test on the wood. This is done to know if there is an existing sealer on the wood. If there is an existing sealer or top coat, the water sealer will not stick.

To perform the test, sprinkle some water directly on the surface and wait for a few minutes.

If the water is absorbed by the wood, it means there is no sealant on it and you can seal it freely. If the water beads on the wood, you’ll need to strip the sealer off first with a chemical-based paint stripper.

2. Prep The Surface

The next step is to carefully prep the surface. Start by dusting and vacuuming loose dust and debris off of the wood with a duster or vacuum.

Next, use a rag and degreaser or Trisodium phosphate (TSD) to wipe off the wood. This ensures that the surface is clean and free of contaminants. When the wood is dry, sand it with 220-grit sandpaper and remove the dust.

3. Sand The Wood With 320-Grit Sandpaper

The purpose of doing this is to smoothen the wood. Paintbrushes and rollers don’t work well on rough surfaces so you need to ensure that the wood is smooth before applying the sealer. After sanding the wood, cover the parts you don’t want to seal with masking tape.

4. Pour Out The Thompson Water Sealer

The next step is to pour the water sealer from its container into a clean bucket or large bowl. You should then stir the sealer gently with a paint mixer. This is to allow you to get easy access to the sealer when applying the coats.

5. Apply The Water Sealer

If you are using a paintbrush, dip the brush into the water sealer, shake off the excess sealer gently, and apply the sealer to the wood.

Ensure to apply the sealer in the direction of the wood grain and not against it. Don’t draw back strokes of the brush or you’ll create scratches and brush marks in the finish. Instead, start the application from one end of the surface and run the paintbrush to the other end. Apply enough coats for good coverage.

If you are using a roller, pick a short extension pole so you can have more control over each coat of the sealer. To apply the sealer, dip the roller into the sealer and roll the applicator on the inner part of the bucket to remove the excess sealer.

After, you can apply the sealer to the wood. Unlike using a paintbrush, you can overlap the roller while applying the sealer because each lap would be even as long as the surface is smooth. Apply More Coats if needed and leave the sealer to dry for at least 24 hours.

Does Thompson Water Seal Need To Be Shaken Before Application?

You need to shake the Thompson water sealer before application if you want to spray the water sealer. The purpose of shaking the sealer is to mix its content so you can get an even and smooth spray on the surface.

If you don’t shake the sealer, you’ll struggle to get smooth coats. If you want to brush on or roll on the water sealer, you don’t need to shake the container. Instead, you need to pour out and stir the content gently.

Final Words

In summary, you can apply Thompson water sealer using a paintbrush, sprayer, or roller. The method you decide to use depends on your level of experience and the surface to be sealed. If the surface is rough or uneven, you should use a sprayer but if the surface is smooth, you can use a roller or a paintbrush.

Whichever method you decide to use, you can find a guide for it in this article. To ensure that the finish comes out well, you should always follow the manufacturer’s instructions and allow the sealer to dry before using it.

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