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

Thompson’s water seal doesn’t have a colorful finish. So, can you paint over it to improve its color?

You can paint over Thompson’s water seal but you need to do a lot of prep work to condition its finish enough to accept the paint. To do this, you need to allow the sealer to dry and then sand and prime it.

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

Compatibility

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

To improve the adhesion, sand the top layer of the sealer off and prime the surface. This way, the paint has a primer coat to stick to.

To know why these two finishes aren’t compatible, you need to know the purpose of the sealer. 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 to its coating. This is done to protect the surface underneath from water.  

However, you can sand and prime the sealer to provide an undercoat that the paint can bite into. This increases the adhesion between both finishes. 

How To Paint Over Thompson’s Water Seal?

Painting over Thompson’s water sealer is a time-consuming task and if you don’t know the right steps to follow, you’ll end up with a 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 finish will not last long since the sealer isn’t designed to be painted. At best, a coat will last about 5 years when used over sealer.

On an unsealed surface, the same coating will last over 8 years. If you want a durable finish, you’ll need to remove Thompson’s 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
  • Paint
  • A primer coat
  • A paint mixer or turning stick
  • Paintbrush or sprayer
  • A vacuum or duster
  • Polyurethane (optional)
  • Chemical-based paint stripper (optional)

1. Prep The Finish

Prep The Thompson Water Seal

First, prep the finish. 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 finish for the primer to adhere to.

You can finish off the 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 Finish

Prime The Water Sealer

The primer helps to increase adhesion between the sealer and the paint. This way the paint will stick over the primer and not the sealer. To apply primer, use a paintbrush and apply 1 coat.

3. Prep The Paint

Prep The Paint

The prep method of the paint depends on the type you want to use. Most water-based paints require you to shake or stir them before using. Some require you to mix the paint with another part before using it. So, check and follow the manufacturer’s instructions to know how to prep it. 

4. Paint Over The Sealer

Paint Over The Sealer

Once the primer coating is dry, apply the paint. To do use, use a paintbrush or sprayer. If you use a sprayer, you must thin the paint (especially for oil-based types). 

You need three coats for proper coverage and protection. Wait until one coat dries before applying the next one. 

5. Seal The Paint

Seal The Paint

Finally, seal the finish. This ensures that the surface doesn’t lose its waterproofing. You can seal it with polyurethane or varnish.

Do You Need to Remove The Sealer?

If you paint over a sealant 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 Thompson’s water layer that is designed to repel all types of liquids including paints.

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

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

Things To Know

What Happens If You Paint Too Soon?

You shouldn’t apply paint on Thompson’s water seal before the sealer has dried. You need to wait at least 30 days for the water sealer to dry first. If you paint too soon, 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 new coating to stick to the damp sealer. Instead, you’ll end up with a tacky and sticky finish. 

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 sealer, 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. 

Your best bet is to remove the sealer first either by sanding or stripping it off. This way, the paint will stick better and last longer.

Final Words

In summary, you can paint over Thompson’s water sealer but to do this, you need to wipe, sand, and prime the finish first. If you don’t do these, there will be a weak adhesion and the finish will peel off. 

However, painting directly over it isn’t the best idea. It’s best to remove the sealant first, and then apply a new coating over the surface.

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