How to Remove Polyurethane From Wood Without Removing The Stain

Polyurethane protects newly stained pieces by creating a hard surface over the wood to shield it from any damage. Yet, removing polyurethane without affecting the stain isn’t easy for many people. Don’t worry, with the right information, you can learn how to remove polyurethane from wood without removing the stain effectively.

How to Remove Polyurethane From Wood Without Removing The Stain

There are two different ways in which you can remove polyurethane from your piece of wood. Both methods aim at removing the hard polyurethane surface without affecting the stain under it.

These methods include: 

• Using commercially available solvents
• Mixing some homemade solutions to develop a mild stripper

The end product in both cases isn’t strong enough to remove the stain along. That being said, you’ll still need to be careful and gentle enough for the best results. 

Note: Its a lot easier to remove polyurethane without having to worry about the stain!

Method One: Using Lacquer Thinner and Denatured Alcohol

Since this method involves the use of chemicals, make sure not to apply too much of it when removing the polyurethane. Remember, the point is to ensure that you don’t remove the stain. 

What You Need

• Denatured Alcohol
• Lacquer thinner
• Wood Cleaner
• Steel wool
• Solvent-resistant gloves
• Goggles
• Face mask/respirator 
• Mixing Bowl
• 2-inch paint brush

Step One: Prepare Everything You’ll Need

The first step in this process entails getting the right tools and preparing your workspace. Make sure you have enough ventilation in the room you’re working in. The substances that you will be working with often emit hazardous gases that can harm you.

If you’re working in a room with limited windows and ventilation. You can use two fans: one fan to drive air in and another to force air out of the room. If you are working on a small piece of furniture, you can strip it outdoors.

You will also need protective gloves and eye goggles. If you have underlying respiratory conditions like asthma, you have to wear gas masks. You will also need to cover surrounding items and areas with drop cloths and old used newspapers.

Step Two: Mix the Lacquer and denatured Alcohol

Mix equal parts denatured alcohol with lacquer thinner in an empty paint can. Stir the mixture thoroughly with a wooden stick. At the same time, move any lacquer that might settle on the container’s base or sides.

In this procedure, denatured alcohol acts as a cleaning agent. The lacquer dissolves the paints and vanishes. The mixture has one crucial advantage: While it’s strong enough to remove polyurethane from your wood finish, it’s weak enough not to dissolve your wood or remove the stain.

Step Three: Apply the Mixture on the Surface

Use a regular paintbrush to apply the solvent on the stained wood’s surface evenly. It would be better to overlap the paintbrush strokes. Doing this provides complete coverage slightly.

I recommend that you stroke the area about three times for better results. This ensures that you cover every part of the polyurethane. You can use a smaller brush (like an old toothbrush or bristle brush) to work on curves and narrow gaps.

Step Four: Wait for Ten Seconds and Then Remove the Mixture

Give the mixture ten seconds to soak the wood and affect the stain beneath. Then immediately use #0000 steel wool to scrub away both stripper and polyurethane. If you want it to take longer, you can cover the surface with a plastic tarp to keep it wet.

Step Five: Clean the Surface

After removing the softened residue, apply wood cleaner on a soft piece of cloth, and wash away. Rinse the surface with warm water and a clean, soft piece of rag. 

Method Two: Using Homemade Solvents and Sandpaper

This method involves a combination of solvents and a fine sandpaper to remove the polyurethane. 

What You Need

• Vinegar
• Corn Scratch
• Baking soda
• Sand Paper
• Wire brush
• 60, 80, and 120-grit sandpaper
• Two mixing bowls

Step One: Prepare Your Mixture

Mix one cup of cornstarch in four cups of warm water to form a paste, then add another four cups of water.

Mix one tablespoon of vinegar with half a cup of baking soda in a separate bow. Stir well and then add the outcome to the first mixture. 

Step Two: Apply the Mixture on Your Wood Surface

Use a paintbrush to apply the solution to the wood surface. Give it around ten minutes to sit nicely on the wood. Ensure that you do not leave the solvent on the surface for too long that it reaches the stain beneath. 

Step Three: Scrub the Surface

When you are confident that it is wet enough, use a wire brush to scrub off the polyurethane and stripper residue . Be gentle and careful not to scratch the wood with the wire bristle.

The mixture is too gentle on the stain and will not discolor your wood. Therefore you need to give it a few minutes to dry.

Step Four: Sand the Surface

For perfect results, you will need to divide the sanding process into stages. In the first step, you will use 60-grit sandpaper, then 80-grit.  To have the best outcome, use the 120-grit sandpaper to apply the last touches.

It would help if you sanded along the wood grain in one direction. When done with the sanding part, use a soft cloth or towel to wipe off any dirt from the surface.

Can I Sand-Off the Polyurethane Without Employing Other Methods?

No, I strongly recommend against it. You can sand-off the polyurethane finish but only at the end of stripping.  You can always use sandpaper to remove the residue from your wood. It also makes the surface smoother for the next painting.

Points to Note When Removing Polyurethane From Your Wood Surface

Below are relevant points that you must head anytime you are removing polyurethane from your wood panel

Avoid Steel Wool on Water-Based Strippers

Do not use steel wool on water-based commercial strippers. It is perfect for removing the softened polyurethane finish. However, it leaves particles that react with oxygen to form rust. It might later discolor your wood panel and destroy your project.

Clear Your Working Area

At the end of your project, ensure that you dispose of the residue, stripper, and any rags you used. You can do this in your nearest community waste disposal area that accepts this kind of waste. Also, clean any tools like putty scraper or brush you intend to keep for your next project.

Bottom Line

Striping polyurethane from woodwork without removing the stain is not rocket science. However, it does need some care. You must apply a specific approach to avoid stripping the stain and the correct strippers and tools in the right proportions.