How to Seal Painted Wood For Outdoor Use

How to Seal Painted Wood For Outdoor Use

We are both aware of how critical it is to seal our outdoor woods because sealant contains UV blockers that reduce the sun’s graying and fading effects on our outdoor furniture.

But, if done wrongly, the protective barrier won’t be durable enough to withstand whatever gets thrown at it. As such, the exterior wood will begin to rot, fade, and chip sooner than expected.

So how you apply it is as equally important.

In this article, I’m going to show you how to seal painted wood for outdoor use the right way – in 5 simple steps.

Is it Necessary to Seal Painted Wood?

Is it Necessary to Seal Painted Wood

Relying solely on the exterior paint alone is willful ignorance that often leads to a valley of disappointment.

There is no doubt exterior paint indeed has the virtues needed to combat against environmental elements, but how can it withstand the ruinous wrath without putting on the extra vest?

The paint’s coverage alone can’t endure the impact that long. Sooner or later, the coat will start peeling, fading, and chipping.

At this point, the external forces have already knocked the only line of defense off the front page, leaving the wood exposed. I guess you already know how to story ends.

However, if you are willing to go the extra mile applying a sealant, you won’t regret it. And here is why:

The sealant suitable for painted wood deposits a highly durable and protective coating on the paint, which helps prolongs its longevity and strength.

Thus, making it overprotective against rot or moisture seeping in through condensation, which gradually leads to crack. The wood will remain heal and hearty throughout spring, summer, fall (autumn), and winter.

Aside from that, it adds a layer of depth and shine that contributes to the woods esthetic. And, it’s easier to clean spills and marks without damaging the paint underneath.

Now that is out of the way, how can you seal an already painted wood for outdoor use?

First and foremost, you need to:

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Choose The Right Sealant

How to Seal Painted Wood For Outdoor Use

Before you can successfully seal a painted wood, you need to choose a sealant that fits your purpose.

There are dozens of sealants on the market, some of which are applicable on both bare and painted wood surface.

However, we have narrowed it to four sealant archetypes that are suitable for use over painted wood.


Polyurethane topcoat can seal exterior paints on wood to help prolong the life of the finish, although it emits toxic fumes. And cleanup requires mineral spirits or paint thinner.

Furthermore, there are two categories of polyurethane sealant, namely water-based and solvent-based polyurethane.

Water-based polyurethane is suitable for latex and acrylic painted finishes. Whereas, solvent-based polyurethane is ideal for oil-based paint.

Don’t use solvent-based polyurethane for latex/acrylic finish and vice versa, unless you are down to experience rampant flaking.


Polycrylic sealants contain polyurethane resin but are low-VOC. They appear white or milky when wet, but turns clear once dry. Although they hold up well with flat latex paint and are easy to clean with water, but won’t bond to an oil-based solution.

Also, they are not as durable as the polyurethane. Many people prefer polyacrylic because it is less toxic, lest they forget potential long-term adhesion problems will catch up with them later.

Paint-and-sealer combination

Evidently, you can tell it is the combination of both paint and sealer – all in one gallon.

If you’re using this type of products, you don’t need additional topcoats because the sealer is contained within the paint mixture.

These products are at their peak when painting furniture with light color or white, as they are less prone to discoloration.

Although some sealants (even polyurethane) experience discoloration as time tick past.

Each one of these products has specific instructions from their manufacturer, so endeavor to read the label on the cans before using them.

The strategy we have compiled on how to seal painted wood for outdoor use, however, fits when applying polyurethane or polyacrylic sealants, so keep that in mind.

Read Also: Best Paints For Outdoor Wood Deck

How To Seal Painted Wood For Outdoor Use

How to Seal Painted Wood

Step 1: Prepare the surface

The first thing is to ensure the final coat of paint is thoroughly dry.

Secondly, you should apply 220-to-320-grits sandpaper lightly, using just enough pressure to level any rough spots, before wiping down the surface with a tack cloth to remove any sand dust.

Step 2: Prepare the sealant

Once the wood is ready, it is time to prepare the sealant.

You have to mix the binders and pigment thoroughly by stirring it with a long, clean stick.

This step is crucial because separation is familiar with most sealant as it sits. But by stirring, it blends all the components, making it work more efficiently when applied.

Do not stir it so vigorously, as it may introduce bubbles into the fluid. And don’t forget to tap off excess sealant on the edge of the can.

Step 3: Apply the solution

Once you are done preparing the solution, it is time to put your paintbrush at work.

You should paint the sealant evenly, from edge to edge in one direction. If done correctly, it will leave a smooth finish when dry.

There are times when you may experience bubbles or drips. When it occurs, immediately smooth them out with the edge of the paintbrush.

Allow the sealant to dry as recommended by the manufacturer.

Step 4: Prepare the finish for the second time

Use a 220 to 320-grits sandpaper to sand the dried coat, but this time very lightly. Then remove the sand residues with a fresh tack cloth.

Step 5: Seal the wood finally

You should apply the next coat of sealant. You can let it dry, sand, before an adding another coat to make it three – mind you, you don’t have to sand the final coat.

At this point, let the finished piece stand overnight or according to the product’s directions, so it cure before putting it into use.

Read Also: How to Remove Paint From Wooden Floor

How do you seal painted wood outside?

A clear polyurethane topcoat can seal exterior paints and help prolong the life of the finish. This particular sealer is similar to polycrylic except it is available in two forms. Water-based polyurethane is suited for latex and acrylic painted finishes.

Can painted wood be waterproofed?

The experts at Home Improvement Super Pages state, “The problem is that wood is a notoriously thirsty substance, and it is easy for water to get absorbed into the grain itself.” For wood that’s already painted, adding a layer of wood sealant is the easiest method for waterproofing.

How do you seal painted wood?

The best rule to adhere to is to apply at least two coats of sealer directly onto the raw wood. This will protect the wood and create a barrier. Then apply primer to enhance adhesion, return tooth to the surface, and whiten the surface for optimising paint colours you plan to apply over it.

Can Thompson’s Water Seal be applied over paint?

The hydrophobic properties of Water Seal will negatively affect the adhesion of any paint applied over it. Can Water Seal be applied to painted surfaces? No. Water Seal can only be used on bare and uncoated brick, stone or concrete.

Can I put sealer over paint?

Sealant Types. Polyurethane is a synthetic, oil-based varnish that deposits a highly durable and protective coating on painted and bare wood surfaces. It is manufactured in liquid forms that you apply with a brush or in a spray can.

What can I put over paint to seal it?

Both clear soft (or paste) wax and water-based poly products like Polycrylic seal and protect the painted finish in an invisible way and do not change the color of the wax.

Can you clear coat over painted wood?

A fresh coat of paint can give almost any wooden piece, such as furniture, cabinets or room trim, a much needed face-lift. Go a step further and apply a clear polyurethane over the painted surface to help protect the paint, as well as the underlying wood.

Is Minwax Polycrylic good for outdoors?

Polycrylic is not as durable as polyurethane and is meant to be used only on interior surfaces such as cabinets, furniture, and trim. It shouldn’t be used in exterior applications or on surfaces that are subject to lots of wear, such as floors, or that are exposed to water.

Can you polyurethane over paint?

Product Options. Polyurethane can be oil- or water-based, and you can use either kind over latex paint; however, oil-based polyurethane tends to yellow as it ages, whereas water-based varieties stay transparent.

Does paint seal wood?

A well-maintained film of paint over the wood and good paint seals in the joints shed water, thus protecting wood by keeping it dry. Cracked paint seals permit entry of water and contribute to decay.


To round off our guide on how to seal painted wood for outdoor use, we urge you to spend more time with the type of sealant you will use for the job.

It is imperative because if you accidentally use a sealant that is contradictory to the paint finish, you may get a bad outcome. So ensure you are picking the right sealant.

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