Varnish protects wood from scratches, pest damage, and dents. But, after a while, the finish gets old and must be removed. So, how to remove varnish from wood?
You can strip varnish from wood by sanding the finish off. Or by using a chemical-based paint stripper or alcohol-based solvent.
To sand it off, rub the sandpaper against the finish until it wears off and disappears from the surface. Or, if you use a solvent, the chemical-based solvent will dissolve the paint particles of the finish and allow you to wipe it off.
Remove it Without Sanding
You can remove varnish without sanding. But, you must use a solvent, paint stripper, or paint thinner. These products have active ingredients in their formula, such as alcohol and methylene chloride, that dissolve and strip the finish without any sanding required.
Sanding is the most common method of removing polyurethane, lacquer, shellac, and other types of varnishes from wood. However, while sanding removes them, it also leaves dust, filth, and wood shavings behind. So, to avoid all of this, you can use paint strippers.
Paint strippers are chemically active compounds that dissolve the finish by breaking the bond between paint particles and liquefying the coating. After a few minutes, you can wipe off the finish or scrape it off.
Paint thinners and alcohol-based solvents can strip varnish too. Paint thinner, especially lacquer thinner, removes all types of finishes from wood. So, if you don’t want to sand the finish off, you can use a paint stripper, thinning compound, or solvent.
However, no alternative methods will leave your wood in good condition as sanding. While sanding leaves a lot of dust, the surface you have sanded becomes smooth and can be refinished immediately without any extra prep work. Strippers, thinner, and solvents won’t make your wood smooth.
Avoid Removing The Paint Underneath
You can remove varnish without removing the wood stain (or paint) underneath it. To do this, apply a mixture of lacquer thinner and denatured alcohol to the finish. The mixture will soften finish, and after a few seconds, use a #0000 steel wool to remove the mixture and the varnish. This method will remove the finish but retain the wood stain underneath it.
A mix of lacquer thinner and denatured alcohol will give you a thick remover that is strong enough to remove any varnish, but also too thick to penetrate wood quickly.
Since the mixture can’t penetrate wood pores quickly due to its thicker nature, the wood stain underneath the sealant will not be affected. However, you must remove the mixture and the sealant in a few seconds with #0000 steel wool. If you don’t remove the mixture in time, it will affect the wood stain underneath.
How To Remove Varnish From Wood?
Removing varnish from a wooden surface isn’t hard, but you need the right steps. Here they are:
1. Sand The Finish Off
Sanding varnish is the most effective way to remove it. The abrasive side of the sandpaper will be rubbed against the finish. This will wear the finish gradually till it disappears from the wood.
The biggest advantage of it is that it removes all types of varnish. The disadvantage is that it is time-consuming and labor-intensive.
To use this method, you’ll need the following tools and supplies:
- Sandpaper (of different grits)
- A pair of gloves
- Rags
- A vacuum or duster
- An orbital sander for large surfaces.
Here is how to do it:
- Clean and wipe the surface to remove dust nibs and grain that can make the sandpaper dull.
- Use 180-grit sandpaper.
- Attach the sandpaper to the sander.
- Sand the varnish off.
- Sand again using 300 or 320-grit sandpaper to smoothen the wooden surface.
- Remove the dust using a vacuum or duster.
2. By Using Paint Stripper
Paint strippers are chemical compounds dissolved in a solvent; the solvent breaks down the bond between the varnish and the surface, causing the finish to swell and separate.
The advantage of this method is that it is quick as it can strip any type of varnish in minutes. The disadvantage is that chemical-based paint strippers won’t leave the wood smooth.
To use this method, you’ll need the following tools and supplies:
- Paint stripper (chemical-based or water-based)
- A paint scraper or putty knife
- Rags
- Steel wool (#0000 wool pad)
- A pair of gloves
- Breathing protection
- Mineral spirits
Here’s how to use it:
- Put on gloves and safety goggles.
- Apply the paint stripper to the finish.
- Wait a few minutes for the paint stripper to work (The wait time is indicated on the container).
- When the finish starts to bubble up, scrape it off using a scraper or #0000 steel wool.
- Wipe off the leftover varnish with a rag.
- After removing it, wipe the wood with diluted mineral spirits to neutralize and remove paint stripper residue.
Tip: Always follow the manufacturer’s instructions when using paint strippers.
3. Using Paint or Lacquer Thinner
Paint thinner or lacquer thinner can strip different types of sealants. Lacquer thinners contain active ingredients that help to thin or dissolve varnishes.
To use this method, you’ll need the following tools and supplies:
- Lacquer thinner (denatured alcohol also works)
- Rags
- Plastic putty knife
- A plastic container
- A pair of work gloves
Here’s how to do it:
- Use safety goggles.
- Pour lacquer thinner into a plastic container.
- Dampen a rag with lacquer thinner.
- Use the dampened rag (not soaked) to wipe the finish repeatedly.
- Wait for a few minutes.
- When you start to see changes in the color or appearance of the finish, scrape it off using a plastic putty knife.
How Soon Can You Re-paint Wood?
You must wait 24 hours before re-painting wood after removing varnish from it. However, the wait time depends on the removal method you used.
If you removed the finish by sanding, the surface will be ready for new paint immediately. This is because sanding makes wooden surfaces smooth and ready for paint.
However, if you used a solvent or paint thinner to remove the sealant, you must wait 24 hours. This is because the surface needs to dry and you need to remove paint thinner residue from it.
Generally, if you use solvent or chemical products on the wood while removing varnish, you must neutralize the surface first using mineral spirits. Then leave it to dry and settle for at least 24 hours before repainting. However, if you removed it by sanding or scraping, you can repaint the wood in about 30 minutes.
Other Products You Can Use:
Vinegar
Vinegar can strip varnish because it has an acidic formula. Being a mild acid, vinegar can dissolve and liquefy the finish so it becomes easier to wipe it off.
However, using vinegar to strip the sealant completely will take time, effort, and lots of vinegar. So, it’s best to choice a different method.
Acetone
Acetone can remove fresh varnish coatings, but it will struggle with cured coatings.
If you accidentally applied varnish and want to remove it, acetone will work fine. This is because the sealant is still in its drying stage and at this stage, it can be dissolved in an alcohol-based solvent like acetone.
However, if the sealant has cured (fully dried) or is a couple of days old, acetone can’t remove it.
Turpentine
Turpentine can strip acrylic varnish but it won’t strip oil-based varnish, such as polyurethane. This is because turpentine is not strong enough to dissolve oil-based or multiple layers of the sealant.
However, you can use turpentine to soften the coating before using another removal method. You can also soak your painting equipment in turpentine after applying varnish to make cleaning easier and faster.
Mineral Spirits
Mineral spirits won’t remove varnish because the solvent is not strong enough to dissolve or strip the coating. At best, a bottle of mineral spirits will only soften the finish so it can be scraped off or wiped off using a steel wool or paint scraper.
Bleach
You should never use bleach to remove varnish. That’s because bleach is an acidic compound that will etch, discolor, and damage the wood.
White Spirits
You can’t remove varnish completely using white spirits because white spirit is a petroleum-based solvent and will struggle with removing waterproof sealants like varnish. However, you can use white spirits to thin, clean, and wipe small stains from wood.
Final Words
Stripping varnish from wood is easy if you use a proper method. But, if you plan on refinishing the wood as fast as possible, sanding is your best bet. Sanding will leave you with a smooth and ready-to-be-finished surface.
