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Can You Polyurethane Over Varnish? (Answered)

Polyurethane is also known as an oil-based finishing coat used mostly in wooden furniture and interior work to enhance the texture of the surface. In this article, we will discuss the results of applying polyurethane over varnish.

Can you polyurethane over varnish?   

You can apply polyurethane over varnish. It’s made of high amounts of resins that help the surface to become long-lasting, durable, and hard-wearing. The resin materials used to make the polyurethane prevents the outdoor environment conditions to cause any damage to the polyurethane-enabled surface. 

Generally, polyurethane is best suited for woods. Applying polyurethane over a varnished floor makes the surface harder and more durable. It will also help the surface to maintain its natural texture and the color of the varnish is applied.

If you are looking for fast drying and even-looking solution for your wooden interior and furniture, you can rely on a polyurethane-based clear coat for the finishing.

The biggest advantage of using polyurethane over varnish is, you can apply the topcoat over an old polyurethane coat without taking it off. Polyurethane will enhance the glow of the wooden surface as well as make it durable.

If you apply multiple layers of polyurethane over a varnished surface, it will make a thicker protective layer over the surface. The following shows how polyurethane works over different varnishes:

Paint polyurethane:

Painting polyurethane is the best choice to use over varnish. It will create an even texture and smooth surface.

Moreover, the painting will a proper amount of polyurethane will cause a thicker layer that will stay longer on the surface and make it harder and more durable. 

Spray polyurethane:

Spraying polyurethane is a time-saving and easy job for anyone without any expertise in such an area.

Spraying puts a thinner layer over the wooden surface so it will help the polyurethane will allow it to dry quicker and the amount of polyurethane will be enough to coat every part of the wood.

Water-based polyurethane:

Water-based polyurethane helps to dry quicker than the traditional oil-based ones because it contains organic and water-based elements. Applying It over varnish will allow you to apply more coats in a shorter time. 

Is varnish compatible with polyurethane? 

Polyurethane suits best when applied over varnish. Polyurethane is usually an oil-based topcoat finish that provides durability in hardwood surfaces, makes the wood long-lasting, and enhances its texture and color.

Making the polyurethane a little bit thinner when applying over varnish will provide you with the best results. Applying polyurethane over varnish will add an extra layer of protection and make it look even and smooth.

Moreover, the polyurethane-based varnish is compatible to use over varnish because it protects the surface and the varnish from damage due to UV rays coming from sunlight, higher temperature, and water.

Your varnish texture might get damaged if it gets in contact with water, applying polyurethane over the surface will help it prevent water from damaging the varnish texture.

Can you poly over varnish without sanding? Can you apply wipe-on poly over a varnish?

It is not recommended to use polyurethane over varnish without sanding. Doing so will not give the best results. Sanding over varnish will smoothen the surface and block any holes over it.

If polyurethane is applied over varnish, it will enhance the texture, resulting in a glossy surface to make it look more even and smooth. Direct applying polyurethane over varnish might make the surface rough and faded.

Not sanding well might cause bubbles and cracks to come in the newly coated surface.

You can wipe on poly over a varnish. It will not cause any damage to the varnish’s texture. Just simply apply the first layer of polyurethane over the varnish and wait for a couple of minutes to set and dry.

Then wipe the excess polyurethane off and go for the second coat. In this way, you can apply multiple coats of polyurethane over the varnish without even damaging the texture of the varnish.

Wiping off a bit early will even the surface smoothly as the closest part to the surface dries first and quicker. 

Can you put polyurethane over all varnishes? 

You cannot put polyurethane over all types of varnishes. Some might cause damage to the texture of the varnish. You can apply multiple coats of polyurethane over varnish but before that make sure to test a smaller portion of the surface to check if it does fit or not.

Applying polyurethane over varnish will make the surface durable and hardened. But, not all type of varnish acts the same as polyurethane. Some might damage the texture as well.

The following shows how different types of varnish reacts when polyurethane is applied to it:

Spar varnish:

Spar varnish is dedicated to providing a higher amount of water resistance. But applying polyurethane over spar varnish is not a good decision. Polyurethane has a lower oil ratio compared to spar varnish.

You can rather sand the old spar varnish properly and then apply some type of varnish on top of it. This will give you the best results.

Oil-based varnish:

In cases of oil-based varnish, sanding the surface well will prevent the polyurethane to peel off from the surface. It will also prevent bubbles or cracks to show up over a new coat.

When brushing polyurethane over an oil-based varnished surface, try to paint long strokes from one end to the other. The right oil allows the varnish and polyurethane to dry faster.

Letting it sit for a couple of minutes to dry up will help to paint another second coat on top of it. It will also increase the lifespan, prevent water from causing any damage to it as well as protect the wood from UV ray damage. 

3 reasons why you can put polyurethane over varnish

There is no doubt that polyurethane does not cause any damage to the varnish. It rather creates a second layer of protection that will protect the wood and the varnish and keep the varnish look newer over the days.

So, maintaining the oil ratio of varnish and polyurethane provides the best result when applying it. The reasons why you can put polyurethane over varnish is discussed below: 

It hardens the texture:

Applying varnish over a wooden surface helps the wood to become long-lasting. But, adding polyurethane over varnish will add an extra layer of protection and make it more durable and hard-wearing. 

It is made of high-value resin:

Due to the high-value resins present in polyurethane, it enhances the glow of varnish resulting in an even, smooth and shiny finish.

Moreover, it also increases the overall lifespan of varnish, allowing protection from a rough outdoor environment.

It is best for finishing:

Varnish will make the wood look livelier and cleaner whereas the Polyurethane will enhance the shine sustain this glow over the years. This will also make the wooden surface smooth and even.

Applying varnish only over wood makes this surface rough, so polyurethane should be added to give it a fine finish. 

How to apply polyurethane over varnish? 

It is very easy to apply polyurethane over varnish if you have the right materials in your range. Make sure to maintain the oil ratio in the polyurethane for best results. You can also thin the polyurethane if you want.

Moreover, a good quality natural bristle brush and a well-ventilated environment are needed to apply polyurethane. It has some high-value resins that enable the surface to become stronger and more durable.

Using an oil-based polyurethane will take a very short time to dry up. Let’s jump on to the quick process on how to apply polyurethane over varnish:

Sand the surface well:

Make sure to sand the surface well before applying the polyurethane. Not sanding well and painting polyurethane all over it might cause bubbles and cracks to come, resulting in an uneven finishing.

Once you’re done with sanding, wipe off all the excess dust and dirt from the surface and make it prepared for the first coat.

Apply the polyurethane:

Once you’ve sanded the surface, it’s time to apply the polyurethane over it. Take a natural bristle brush and soak it well in the oil-based polyurethane.

When brushing over surfaces, make sure to stroke from one end to the other. This will provide an even layer on the surface.

Let it dry:

Finally, let it dry. Usually, it takes 24 hours to dry well. It is a work of patience so you have to be focused when doing it.

After it has completely dried up, sand is well again, and apply the second coat. You can apply multiple coats based on your preference on you hardened you want to make the surface.

Final Thoughts: 

You can apply polyurethane over varnish. It does not cause any damage to the surface, rather it enhances the glow of the wood and makes it durable. But when applying polyurethane over varnish you need to make sure you maintain the proper oil ratio in the polyurethane when applying.