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. So, how to apply it?

To apply Thompson’s water sealer, use a paintbrush, roller, or sprayer. A sprayer applies it faster, but you need more experience. While a roller applies it slower, but you can control it easier. 

Before applying it, 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 then apply it. 

Spraying vs Roller (For Thompson’s Water Sealer)

Spraying vs Roller (For Thompson Water Sealer)

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

Sprayers apply it in thin and light coats which makes the sealer dry faster. They also apply it faster, 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 it, from loading up the sealer to assembling your tools and priming the sprayer. If you don’t have any prior experience, you may find it difficult to apply the water sealer perfectly.


  1. It gives good coverage on the surface.
  2. It allows the sealer coats to dry in time.
  3. You to recoat sooner.
  4. Gives the smoothest coat.
  5. Allow you to seal tight corners and crevices.
  6. Applies more sealant.
  7. Works for all surfaces regardless of how smooth or rough.


  1. Requires experience and skill.
  2. Involves a lot of prep work since you need to mask the surface, assemble the tools, and prime the sprayer 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 roll the Thompson’s water sealer. 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.

However, they aren’t designed to make the sealant dry fast. Though you get good coverage, you need to wait a bit longer for each coat to dry because rollers often apply it in thicker coats.


  1. Gives good coverage.
  2. It can be used by beginners.
  3. Doesn’t require much prep work as long as the surface is smooth.
  4. It is a cheap applicator method.


  1. They apply thicker coatings. 
  2. It takes longer to complete it.
  3. They can cause bubbles in the finish.
  4. They only work on smooth and flat surfaces.

So, which one do you need? It all depends on the type of surface you are working. If the surface is rough or has lots of corners and ridges, it’s best to use a paint sprayer as they 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.

Do You Have To Mix or Shake it?

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

If you mix it, 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 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 it using a paint sprayer since they apply light coats.

You need to shake the Thompson water sealer before application if you want to spray it. 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.

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.

Here are the tools you need:

  • 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’s how to do it:

  1. Remove any existing sealer coat on the wood.
  2. Vacuum the surface that you want to seal to remove dust and debris on the surface.
  3. Wipe and clean the wood surface with rags and mineral spirits to remove grease and oils. If you are working on a deck, use Thompson’s deck cleaner. 
  4. Allow the wood to dry fully for 24 hours.
  5. Sand down the wood with 220-grit sandpaper and remove dust.
  6. Assemble the paint sprayer – follow the user’s guide on how to do this.
  7. Load the Thompson’s water sealer in the cup of the spray gun – if the sprayer has a suction hose, put the hose into the sealer container and put the return hose in an empty bucket.
  8. Prime the paint sprayer – to do this, switch the control knob to prime and ensure that the sealer comes out of the nozzle.
  9. Test the spray on a part of the wood to see if the sealer sprays well.
  10. Spray directly on the prepped wood – 2-3 coats of Thompson water seal are enough.
  11. Allow the Thompson water sealer to dry – this takes about 4 – 24 hours.
  12. 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.

How To Roll Or Brush Thompson Water Sealer?

How To Roll Or Brush Thompson Water Sealer?

You can also use a paintbrush or roller to apply it. Both applicator methods work as well as a sprayer when used correctly.

If you want to use a paintbrush, you’ll need a 4-inch paintbrush. 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’s how to do it:

1. Do A Splash Test

First, 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

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 surface. 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 With 320-Grit Sandpaper

The purpose of doing this is to smoothen the surface. 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 it 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.

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

Tony Adams
Tony Adams

Tony is a professional painter and an author of DIY Geeks. Tony has completed over 1,000 painting projects for his clients. It's safe to say he knows what he Is talking about,

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