How to Remove Polyurethane From Wood? (3 Methods)

Polyurethane adheres perfectly to the wood and has a glossy moisture-resistant coating. So, how to remove it from wood?

To remove polyurethane from wood, use a paint stripper, vinegar, or sand it off. To sand it off, use coarse-grit sandpaper (150-grit). The sandpaper will remove it and leave a smooth wooden surface behind.

A paint stripper will remove multiple coats of polyurethane. The paint stripper will penetrate and dissolve the paint particles of the sealant, making it easier to wipe it off in 15 minutes.

Without Sanding

You can remove polyurethane without sanding. To do this, use a paint stripper or baking soda. The paint stripper will dissolve its coating and liquefy it, making it easier to wipe it off. You can also use a paint thinner instead of a paint stripper. 

However, sanding the polyurethane is the best way to remove it. That’s because sanding doesn’t damage the wood and leaves behind a smooth surface for the next paint (or sealant) to stick to. 

Besides removing it, sanding will also remove the imperfections on the surface, while the paint stripper won’t. Sanding will even out the surface and remove bumps from it. On the other hand, a paint stripper can damage the wood if left for too long.

After removing it with a paint stripper, you must clean (remove) the paint stripper residue, or the next coating won’t stick. 

Removing Polyurethane Without Removing Stain

You can remove polyurethane without removing the wood stain underneath by using a mild paint remover. A water-based mild paint remover is not strong enough to affect (remove) the stain, but it will remove the polyurethane. However, leaving the mild paint remover for too long will also remove the stain.

Also, you can use a mixture of denatured alcohol and lacquer thinner to remove it without affecting the stain. But, you must wipe off the mixture within 15 seconds to prevent it from penetrating the stain finish. 

Removing polyurethane without removing the wood stain underneath doesn’t always work. You will often notice etched spots on the stain, especially if you leave the paint remover for too long. You must apply a fresh coat of wood stain to hide (cover) these etched spots.

How To Remove Polyurethane From Wood?

Removing polyurethane from wood isn’t hard, but you must use the right methods. If you use the wrong method or tools, you can damage the stain or the wood surface. Here are 3 methods that you can use:

Method 1: By Sanding

The best way to remove polyurethane is by sanding it off. The abrasive side of the sandpaper will remove the glossy layer of the sealant and smooth out the wooden surface. 

Here are the tools you need for this method: 

• Sandpaper
• A pair of gloves
• Breathing protection
• A sander (if necessary)

To remove it from a floor, you must use a floor or orbital sander.

Here is a guide for this method:

1. Clean the surface to remove debris that can damage the sandpaper. 
2. Attach the sandpaper to the bottom of the sander. 
3. Sand it off.
4. Remove the sanded dust.
5. Clean the wood. 

You must frequently check the surface while sanding to know if the sealant has been removed. If you continue sanding after the polyurethane has been removed, you’ll gouge the wood.

Method 2: Using Paint Strippers

You can use a paint stripper to remove polyurethane. The paint stripper will soak into the sealant and dissolve it, making it lose its bond to the wood. This will cause the finish to bubble up and peel off.

To use this method, you’ll need:

• A paint stripper
• Paint scraper
• A pair of gloves
• Plastic putty knife
• Clean rags
• Wire sponge

Here is a guide for this method:

1. Clean the surface using clean rags.
2. Apply a layer of paint stripper.
3. Wait for 20 minutes.
4. Inspect the coating; if the polyurethane has developed bubbles, remove it. 
5. Remove it by scraping and wiping it and the paint stripper off the wood. 
6. Re-apply the paint stripper over the leftover.
7. Clean the wood with warm water to remove paint stripper residue. 

Tip: You must always follow the manufacturer’s instructions when using a paint stripper.

Method 3: Using Baking Soda and Vinegar

You can also remove it by using a mixture of baking soda and vinegar. Baking soda is an alkaline substance, and vinegar is considered to be acidic. Mixing both will create a good polyurethane stripper.

To use this method, you’ll need:

• Baking soda
• Vinegar
• A clean bowl
• Turning stick

Here is a step-by-step guide:

1. Mix equal parts of baking soda and vinegar in a clean bowl.
2. Add a cup of warm water.
3. Stir the mixture using a turning stick.
4. Apply the mixture to the finish.
5. Wait until the finish starts to bubble. 
6. Use a scraper to remove it.
7. Wipe off excess baking soda or polyurethane.

Tip: While scraping, ensure to do so along the wood grain.

Other Methods/Products Use Can Use:

Next, let’s check out other methods and products that you can use:

Acetone

Acetone is a great paint remover. However, acetone can’t remove cured polyurethane because the liquid isn’t strong enough to dissolve it. If the finish is over 3 days old, acetone won’t remove it. 

Lacquer Thinner

You can use lacquer thinner to dissolve and remove polyurethane. Lacquer thinner can remove topcoats such as polyurethane, varnish, and lacquer. However, don’t let the lacquer stay over the wood for too long as it can discolor it.

You can use lacquer thinner to clean polyurethane brushes too. 

Alcohol

Alcohol can remove fresh polyurethane, but it won’t remove cured polyurethane. To remove it with alcohol, use denatured alcohol. That’s because denatured alcohol is the most potent at removing a sealant.

However, if the finish has cured, you must mix denatured alcohol with another solvent (such as lacquer thinner) to remove it. That’s because denatured alcohol can’t remove cured sealants on its own. 

Citristrip

You can use Citristrip to remove polyurethane. Citristrip is an industrial-strength remover that removes multiple layers of paint and sealant. This paint remover will remove fresh and cured finishes within minutes. 

Methods/Products You Should Avoid:

TSP (Trisodium Phosphate)

TSP (Trisodium Phosphate) is an alkaline-based cleaning agent that is not strong enough to remove it. This cleaning agent is used to clean, degrease, and remove dirt from different surfaces, but it can’t remove dried sealants. 

The best TSP will do is to gunk up the finish or make it sticky.

Turpentine

Turpentine can soften polyurethane, but it can’t remove it. So, you can use turpentine to soften it and then use a paint remover to remove it. 

Mineral Spirit

Mineral spirit isn’t strong enough to dissolve and remove polyurethane. So, you shouldn’t use it. Mineral spirit is a petroleum-distilled solvent that removes latex and oil-based paints. But, can’t remove top coats.

Goo Gone

Goo gone can’t remove polyurethane. You can use Goo gone to remove stains and dirt from surfaces. However, goo gone isn’t strong enough to penetrate or dissolve a sealant. 

Final Words

You can remove polyurethane from wood using a paint stripper, paint thinner, baking soda and vinegar, or sanding it off.

To remove polyurethane without affecting the stain (or paint) underneath, use a mixture of lacquer thinner and denatured alcohol over the finish for 15 seconds and wipe it off. 

Always read and follow the manufacturer’s instructions before using a paint stripper or remover.