How to remove polyurethane from wood: several methods and more

Polyurethane coating is a widely used furniture material. It increases the durability of the wooden piece and makes the appearance better.

But it does have its downsides – some kinds of polyurethane get yellow over time, while others get damaged by alcohol and acids.

Or it just might be applied to the wrong place on the wood, so you want to remove it without causing problems.

In this article, we will explain to you how to remove polyurethane from wood, and give some examples of good products for doing so.

What is polyurethane? And how to remove polyurethane from wood safely?

Polyurethane is a liquid plastic-like covering that forms a protective layer on the wood surface. It consists of a synthetic material that is basically a sort of plastic. Once applied and dried out, it forms a long-lasting and cleanable surface.

If you’d like to remove this coating for some reason, you could just sand the surface until the polyurethane layer is removed, and wood particles start to appear. But this is an arduous task, and the easier way is to use a special chemical – polyurethane stripper.

But before you choose a proper chemical product and start removing polyurethane, you should get familiar with different sorts of coating.

There are two major types of polyurethane – water-based and oil-based. They both have their upsides and downsides, which we will briefly describe below.

Water-based vs. Oil-based polyurethane

Water-based polyurethane can be damaged by excessive heat. It is also prone to chemical damage, e.g. by acids or solvents like alcohol.

That is why water-based polyurethane is more suitable for wooden pieces that are not cleaned using chemicals or put under the sun’s heat. These include picture frames, bookcases, etc.

Oil-based polyurethane, on the other hand, tends to tint the wood, so you get the yellow surface effect over time. This eliminates the natural richness of color and texture.

Oil-based polyurethane is more suited to countertops or tabletops since they are often subject to cleaning and friction.

The oil-based version is usually more durable than the water-based polyurethane, especially in terms of resisting chemicals and heat.

The oil-based polyurethane is higher in volatile organic compounds (VOC). It means that it’s better to work with it in a well-ventilated space. You should also wear a respirator when working with any type of polyurethane.

Polyurethane can be applied over acrylic or latex paint on the wood surface, which will increase the durability of the paint layers. The oil-based polyurethane will gradually change the color of the paint.

What is the easiest way of polyurethane removal?

There are various ways of removing polyurethane from wood. The most convenient one is using a chemical stripper. It allows you to remove the coating quickly and conveniently, but it is still a bit risky.

Read on to know what the risks are.

But before discussing how to remove polyurethane from wood and how to use strippers properly, we will give you some examples of good polyurethane strippers.

The list of the best polyurethane strippers

SUNNYSIDE CORPORATION 2-Minute Paint Remover Advanced Gel (The fastest)

This methylene chloride-free remover can quickly get multiple layers of paint or polyurethane off many different surfaces, including wood. The thick gel formula allows you to use the remover on vertical surfaces, too.

The chemical paint stripper gel works on various surfaces such as oil- and water-based paints, lacquer, shellac, epoxy, varnish, and, of course, polyurethane.

The one-gallon container can be used to cover 100 square feet.

DUMOND CHEMICALS SmartStrip Advanced Paint Remover (Environmentally friendly)

This Dumond Chemicals remover is biodegradable and does not contain any VOCs, so it is safe to use with plants and animals nearby.

The formulation is water-based, manufactured without using caustic chemicals or harsh solvents, and odor-free. It is not just only environmentally friendly – it is great at removing multiple layers of paint, varnish, shellac, and polyurethane from wood.

More than that, this chemical paint stripper is pH-neutral, which means that it does not need any post-strip neutralization.

SUNNYSIDE CORPORATION Multi-Strip Advanced Paint Stripper (The most convenient)

Another product from Sunnyside Corporation offers you a trigger spray stripper. This product is really convenient since you will not have to use a paint brush with it.

The formula is fast, has a low odor, and is environmentally safe. It is also non-drip, which means that the paint stripper can be used for vertical surfaces.

The chemical works in just 30 minutes, after which you need to do a simple clean-up using just water.

If you do not want to work with a paint brush and want a simple and convenient solution, this Sunnyside trigger spray stripper is for you!

Guide to removing polyurethane from wood using a chemical paint stripper

Once you select your type of polyurethane stripper, you can figure out how to remove polyurethane from wood.

It does not matter whether you are removing it from furniture, doors, flooring, etc. The steps will be practically the same.

But before starting to remove polyurethane from wood using a chemical stripper, you must take some precautions.

Precautions

Polyurethane coating contains highly toxic substances, especially if it is oil-based. You want to avoid inhaling those compounds, so, to stay safe, you should take the precautions listed below:

• If you don’t possess a well-ventilated space, use water-based strippers instead of chemical-based ones. Only well-ventilated workspaces allow you to work with chemical-based products safely.
• You must wear rubber gloves when working with a chemical stripper.
• Your clothes should protect your skin. Wear full-coverage clothing: a long-sleeved shirt, and long pants.
• Wear safety goggles.
• Wear an appropriate mask if you are working with products containing methylene chloride or mineralized alcohol. You can use a mask, like KN95, as an example.

Preparation of the area

Besides covering yourself with proper clothing and putting on rubber gloves and goggles, you should prepare your workspace.

First, protect the surrounding area by laying down some drop clothes or plastic sheeting on the floor or pieces of furniture. You do not want the stripper to get onto the surroundings.

For example, if you want to remove polyurethane from a door, then you also should remove the handles, doorknobs, or glass windows, if possible. By doing this, you will be able to reach all the nooks and small areas where the polyurethane is applied.

Things you will need

• Chemical paint stripper 
• #0000 Steel wool (optional)
• Plastic scraper 
• Paint brush or spray
• Wire brush
• Fine grit sandpaper 
• Waxed paper

Step-by-step guide

1. Apply the paint stripper

You can apply the stripper either by using a paint brush or a spray. The tool choice also depends on the type of product.

If the paint stripper you are using requires you to use a paint brush to apply it, take an old paintbrush, the one that you do not mind throwing away.

Generally, chemical-based polyurethane strippers are more effective than water-based ones. But the latter is safer, while chemical-based paint strippers might contain toxic methylene chloride. Water-based strippers might require a second application, though.

Apply a generous amount of stripper to the wood-polyurethane surface. Cover the whole polyurethane coating with a thick layer of the stripper. Use the tip of your paintbrush to reach all the nooks and corners.

2. Let the stripper work

After applying the stripper, wait for it to do its job. The time it needs depends on the stripper type. A chemical stripper would need only about 10 minutes to show some action. If you are using a water-based stripper, it will take much longer.

One important thing: if you feel that the chemical is going to need several hours or more, you should cover the project with something like a plastic tarp. This way, the polyurethane stripper will not dry out too quickly. And paint, varnish, and polyurethane strippers work only when wet.

3. Remove the polyurethane by scraping

You will see when it is time to remove polyurethane and stripper mixture from the surface of the wood. It will be wrinkling, bubbling, and lifting.

Then you can take a tool like a paint scraper and scrape the surface. It is better to work along the direction of wood grain since it decreases the chance of damaging the wood while scraping. Also, it is safer to use a plastic scraper instead of a metal one.

By the point when you remove most of the polyurethane coating, you might notice some areas where the second application of stripper is needed.

After you have done the whole process, you need to neutralize the residue. Use an after-wash for paint stripper, or, if you are using a water-based stripper, just rinse the wood with water.

4. Use #0000 Steel wool if needed

You can use a small wire brush to get to the tricky areas on your wood, like corners and decorative parts. Steel wool would work just as well.

#0000 Fine steel wool is perfect for removing polyurethane without damaging the wood surface.

5. Finish by sanding

If you are using a water-based stripper, your clean-up will be easy just with water. Once you have removed all the polyurethane you wanted to get rid of, you can remove the drop cloth. Then dispose of the polyurethane and stripper residue.

If you plan to refinish the wood surface with a stain, paint, or varnish, you will need to sand the whole surface first. Take 100-120 grit sandpaper to get a smooth and clean finishing.

The wood is supposed to be completely dry before you apply any coating.

After successfully removing polyurethane and covering the wood with a coating of your choice, you can enjoy the result!

Tips and tricks

• When choosing a paint stripper for polyurethane, keep in mind that water-based strippers are generally less effective than chemical-based ones. They take significantly longer to work and may dry out before you notice any action.
• You can use vinegar to remove polyurethane from wood. Especially if it is a water-based polyurethane. The acid in vinegar breaks down the material, making it easy to remove with a scraping tool. But this method is less effective than using specialized products.
• If you are not sure whether your coating is polyurethane or something else, you can easily test it. Take a cotton ball, soak it in acetone, and hold it against an inconspicuous area of the wood surface for a couple of minutes. If it starts to stick to the surface, the wood is covered with shellac, lacquer, or varnish. If it does not, then it is polyurethane.
• You cannot stain the wood properly if the polyurethane is not removed. This material blocks the pores of the wood, so the stain does not reach them. But you can still apply a gel stain over polyurethane.
• Do not hesitate and apply a liberal amount of stripper. A thin layer of it will dry out too quickly and will not do the job. A thick coat will stay wet longer and be way more effective.

Methods to remove polyurethane from wood without a stripper

If you do not want to work with paint strippers, it is still possible to remove polyurethane from wood without using harsh chemicals!

First method: home-made varnish remover from household items + sanding

This method uses homemade varnish remover instead of commercial chemical paint strippers. We will give you the recipe for this remover and describe the whole process of removing polyurethane.

Things you will need

• Hot and cold water
• A bucket, cup, and tablespoon
• Paintbrush
• Wire brushes, or 3M Heavy duty stripping pads
• Fine grit sandpaper
• Cornstarch
• Baking soda
• Vinegar

Step-by-step guide

1. Make the varnish remover

Here’s the short list of ingredients needed to make the mixture:

• 4 cups of hot (boiled) water;
• ½ cup of cold water;
• 1 cup of cornstarch;
• ¾ cup of baking soda;
• 1 tablespoon of vinegar.

Mix 1 cup of starch with ½ cup of water and stir it to get a paste. Then take a bucket and pour 4 cups of boiled water into it. Then add ¾ cup of baking soda and 1 tablespoon of vinegar to the water in the bucket.

Thoroughly stir the mixture in the bucket and then pour the starch paste into it. Stir the final mixture thoroughly again. Now you have your homemade varnish remover ready!

2. Apply the home-made remover

Use a paintbrush or a cloth to apply the varnish remover on your wooden surface. Let the liquid dry for 3 to 5 minutes.

3. Scrub with wire brushes or stripping pads

Scrub the wood surface using wire brushes or stripping pads. Do not be afraid to apply some pressure if necessary. Work until you stop feeling slickness. That is the point when all of the polyurethane is removed.

4. Sand the wood

Now all you need to do is refine the surface by sanding. Start with 60-grit sandpaper and gradually work it up to 120-140-grit. In the end, you should have smooth and clean wood.

Second method: home-made varnish remover, NO sanding

It is possible to remove polyurethane from wood without sanding, too. Here’s a simple method of doing it.

Things you will need

• Lacquer thinner
• Denatured alcohol
• Wood cleaner
• Wooden stir stick
• A bucket or an empty paint can
• #0000 Steel wool

Step-by-step guide

1. Make the varnish remover mixture

Mix some lacquer and denatured alcohol in a small bucket or another suitable container. Stir the mixture with a wooden stir stick. This will be your homemade polyurethane stripper.

2. Apply the home-made varnish remover

Take a brush or cloth and apply the remover to the surface with them. Then wait for several minutes until the mixture starts working.

3. Remove polyurethane using steel wool

Now use the steel wool to remove the polyurethane and stripper mixture from the wood. As mentioned before, the #0000 mark is fine steel wool that works perfectly.

4. Wash and clean the wood without sanding

This step is necessary only if there is some stripper residue left. Use the wood cleaner to wash the wood, then rinse the surface with warm water.

Now we have covered all of the most convenient and effective methods. If you still have some questions left, you might find the answer to them below.

FAQ

How do I remove polyurethane from skin?

If some polyurethane got onto your skin and has already dried, it is not a big trouble. You can try rubbing vegetable oil or peanut butter on dried polyurethane. This will loosen it and make it easier to get off the skin.

How do I clean polyurethane coating safely?

Avoid using alcohol or ammonia-based cleaners when cleaning polyurethane. Those chemicals gradually damage polyurethane. Wipe the surface with a damp cloth and use natural-based cleaning detergents instead.

Can I remove polyurethane from wood just by sanding it?

Yes, it is possible to remove polyurethane from wood without any chemicals by using sandpaper only.

But it consumes lots of time and energy. You can use a power sander to make it way easier, though.

What is the ideal way to remove polyurethane from wood?

Using a chemical polyurethane stripper is still the most effective way. Most paint and varnish strippers will work on polyurethane, too. These specialized chemicals do not damage the wood.

Can I apply the stain without removing the polyurethane layer?

Polyurethane is a material that blocks the pores in the wood, so the stain will not be absorbed. If you insist on staining without removing the polyurethane, you can go with a gel stain. This kind of stain will bond to polyurethane itself and will act more like paint.

Conclusion

Now you know how to remove polyurethane from wood correctly.

We described 3 ways of removing polyurethane from wood, gave you examples of good paint stripper products, and answered some of the important questions.

We recommend you use the chemical stripper method for the best results. Remember to protect yourself and wear proper clothing as well as rubber gloves and safety goggles when working with chemicals.