Can You Paint Over Thompson’s Water Seal? (Explained!)

DIYers often wonder if they can improve Thompson water seal’s color and finish by painting over it. So, can they?

You can paint over Thompson water seal but you need to do a lot of prep work to condition the water seal enough to accept the paint. To do this, you need to allow the water seal to dry. Then you’ll need to sand and prime the Thompson water seal before applying the paint.

If you don’t prep the water seal, the paint will not stick. The finish you’ll get will be inferior to the normal paint finish because Thompson water seal has a hydrophobic formula.

This post reveals a lot more about painting over Thompson water seal including the expert tips to carry out the task.

Does Paint Stick Over Thompson’s Water Seal?

Paint doesn’t stick to Thompson water seal because the sealer has a hydrophobic formula that repels all types of liquids, including paints. If you apply paint directly over a Thompson water-sealed surface, the paint regardless of if oil or water-based will not stick.

To make a paint stick to Thompson water seal, sand the top layer of the water seal off and prime the surface before applying the paint. This way, the paint has a primer coat to stick to.

To know if paint sticks to Thompson water seal or not, you need to understand the purpose of Thompson water seal. Thompson’s water seal has moisture-blocking substances, the purpose of these substances is to repel any type of moisture. This means no liquid can penetrate or stick, including paint. 

However, you can modify the water sealer to allow the paint to stick. To do this, sand and prime the water sealer before applying the paint. By sanding and priming the water seal, you provide an undercoat that the paint can bite into. This increases the adhesion between the Thompson water seal coat and the paint coat.

How To Paint Over Thompson’s Water Seal?

Painting over Thompson water sealer is a time-consuming task and if you don’t know the right steps to follow, you’ll end up with a very poor finish. Luckily, this guide reveals how to do it in 5 simple steps. However, there’s a downside to doing this.

The downside is that the paint finish will not last long since the sealer wasn’t designed to accept paint. At best, a paint coat will last about 5 years when used over sealer.

On an unsealed surface, the same paint will last over 8 years. If you want a durable finish, you’ll need to remove the Thompson water seal first. This guide also explains how to do that.

Here are the tools that you need:

  • Sandpaper (180-320 grit)
  • A pair of gloves
  • A power sander
  • Rags
  • The required paint
  • A primer coat
  • A paint mixer or turning stick
  • Paintbrushes or a paint spray gun
  • A vacuum or duster
  • Polyurethane (optional)
  • Chemical-based paint stripper (optional)

1. Prep The Thompson Water Seal

Prep The Thompson Water Seal

The first step is to prep the Thompson water seal. To do this, wipe and clean the sealed surface to remove dust, you can do this with a rag. After wiping the surface,  sand it down with 180-grit sandpaper. This creates ridges in the sealer for the primer to adhere to. You can finish off the sealed surface with 220-320 grit sandpaper. Ensure to remove dust with a vacuum or duster after sanding.

If you’ll like a flawless finish, you’ll need to remove the water sealer first. You can do this using coarse sandpaper or a chemical-based paint stripper.

2. Prime The Water Sealer

Prime The Water Sealer

Next, apply a coat of primer to the Thompson water seal. The primer helps to increase adhesion between the Thompson water seal and the paint. You should apply the primer coat with a paintbrush and allow it to dry for 2 hours.

3. Prep The Paint

Prep The Paint

You can prep the paint when the primer dries. The prep method of the paint depends on the type of paint you want to use.

Most water-based paints require you to shake or stir the paint before using it. Some paints require you to mix the paint with another part before using it. So, check and follow the manufacturer’s instructions for your paint to know how to prep it.

4. Paint Over The Sealer

Paint Over The Sealer

Next, apply the paint to the sealer. You can do this with a paintbrush but it’s better if you use a paint sprayer or spray gun. This helps to apply the paint faster and smoother.

You need 3 coats of paint when using a paint sprayer and 2 coats if using a paintbrush. Ensure to allow each coat of paint to dry enough before recoating.

5. Seal The Paint

Seal The Paint

The final step is to seal the paint. This ensures that the surface doesn’t lose its waterproofing. You can seal the surface with polyurethane or varnish.

Remove Thompson’s Water Seal Before Painting

If you paint over Thompson water sealer without removing it, the paint will not stick and will gradually peel off the surface after a while. This is because there is a hydrophobic layer on the Thompson water layer that is designed to repel all types of liquids including paints.

So to paint over Thompson’s water seal, you either have to remove the sealer completely or sand and prime it before applying paint. By sanding, you remove the waterproof top layer of the water sealer and create tiny ridges that primer paint can bite into. The primer coat also allows the paint to stick better to the sealed surface.

If you paint over Thompson sealer without removing it or altering the condition with primer, the paint will crack and fall off in a few days.


Can You Paint Over Thompson Water Seal Before The Sealer Has Dried?

You shouldn’t apply paint on Thompson water seal before the sealer has dried. You need to wait at least 30 days for the water sealer to dry before putting paint over it. If you paint Thompson water seal while the paint is damp, you’ll create a messy finish.

The clash of the hydrophobic properties of the sealer and the solvents in the paint will not allow the paint to stick to the damp sealer. Instead, you’ll end up with a very tacky and sticky finish. Depending on the type of paint that you apply, the tacky paint may begin to smell foul after a few days.

Are There Types Of Water Sealers That You Can Paint Over?

All types of water sealers will repel paint because that is what the sealer is designed to do. However, certain water sealer brands are more accommodating when it comes to accepting paint. For example, polyurethane sealers are more accommodating to water-based paints.

However, as long as you sand and prime the water seal, the paint will have some level of adhesion to the surface. But, the level of adhesion would be better if the water sealer wasn’t there. That’s because the primer, just like the paint, won’t stick properly to the water sealer. However, the primer will stick better to the water sealer than the paint because it has better adhesive qualities.

Your best bet if you want to paint a sealed surface is to remove the sealer first either by sanding or stripping it off. This way, the paint will stick better and last longer than if you apply paint over the sealer after priming.

Final Words

In summary, you can paint over Thompson’s water sealer but to do this, you need to wipe, sand, and prime the water sealer to allow the paint to stick. If you don’t do these, the paint will not stick properly and will peel off of the surface after a while.

However, painting over Thompson water sealer isn’t the best option even after you have primed the surface. That’s because the primer won’t stick well to the sealed surface and when it comes off, the finish will come off with it. The best way to get a good finish over a sealed surface is to remove the sealer first and then apply paint.

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