Varnish or other wood finishes are put onto wood to keep the wood protected, but say you wanted to remove it to refresh or maybe even change the wood finish itself.
You have a few options to do that including sanding, solvents, and chemical strippers.
Based on my own personal experiences, sanding for removing the wood varnish may work only when you have a very thin layer of varnish applied on the surface.
Using a chemical stripper is more effective if you need to remove the sticky varnish layer from hard-to-remove surfaces without getting the surface damaged.
This is due to the fact that wood surfaces that have been well finished, are often coated multiple times, and removing the varnish from these surfaces can be challenging.
These may need extra efforts, patience, and much stronger agents that can help.
No matter whether you need to take the varnish off from your old oak cabinets, antique furniture, wooden doors, tables, chairs, or windows, the chemical-based strippers can work pretty well.
Removing the Varnish from Wood
First things first!
Before you even plan to buy a good varnish remover for your wooden doors, cabinets, or furniture, you should find out if what you’re trying to remove really is a varnish or not.
You can do this by looking at it nicely and closely.
Varnishes are often colored over amber. They will also have brush strokes whereas thinner finishes will not.
You do this because you don’t want to buy a product you don’t need as other things can be removed with just any caustic chemicals.
After you have confirmed the varnish that’s applied on the wood surface, there can be three ways you can use to remove old varnish from wood furniture.
You may check them below and follow the steps mentioned based on the project you have on hand.
Method 1- Sanding
This can be done with just about any sander you have.
It can be much more labor-intensive than some of the other options but if you’re just painting it after it’s done, then it’s all you’ve got to do.
Sand it down and paint over it after wiping it down so that all the dust is gone.
You can use a sander on flat surfaces and wide areas, and tighter smaller spots can be done with some hand sandpaper and some time.
While using sandpaper, start with 150-grit sandpaper to sand down the surface. Then replace it with 220-grit sandpaper and repeat the sanding.
This will completely remove the toughest of the varnish from the surface.
Overall, sanding is a good option for removing a bunch of different things including paint, acrylic, varnish, lacquer, and shellacs.
Method 2- Use Solvents
Some finishes are alcohol-based and can be taken off by using denatured alcohol or thinners.
Once it has been rubbed with a cloth damped with it you can take a simple putty knife to scrape away at it and get it off the wooden surface.
This works pretty fine on shellac and lacquer.
If you find the varnish tough to remove by sanding or after using solvents, you can consider applying some heat by using a heat gun.
This can soften the old varnish making it easy to get removed.
Method 3- The Chemical Strippers
These work well at taking off acrylics, varnishes, and paints but be careful when using them.
It contains chemicals that can be harmful to your eyes, lungs & skin and even the environment.
Luckily, they have improved and become much safer over the years.
You can even use them on furniture made of thin plies and veneers like marine plywood.
Apply it and then use fine steel wool to pull off any residue left going with the grain of the wood.
What Type of Varnish Removers are Best for Wood?
When you know that your project will need a good chemical stripper, you will now need to choose the right varnish stripper product that can help strip the layer without any fuss.
These are some of the chemicals you should aim for removing a varnish:
a) Biochemical strippers
These are by far the safest to use and come from a plant origin hence the name Biochemical.
They come from different citruses and other sources such as pine or pulp and are often seen as safer.
These are chosen because they are much more ECO-friendly and are odorless when you use them allowing them to be much more flexible.
b) Methylene chloride agents
These agents are often the strongest and should be treated as such.
Always wear gloves and goggles as the instructions say when using them.
They often contain other components to help counteract their own strong adverse effects.
Since they are incredibly effective against very heavy varnish coats that you may come across, these can be used as one of the quickest ways to remove varnish.
c) N-Methyl-2-Pyrrolidone strippers
Not quite as good as the previously mentioned Methylene chloride agents but used as a substitute for them due to health concerns.
These are far safer but at the same time strip the wood just a little worse.
They sometimes have more caustic chemicals in them but much less of them, making them a lot safer to use.
They cling to the wood well, and they do a fair job at removing the varnish, the biggest concern they bring to the table itself is that they are flammable.
Precaution and Tips When Using Varnish Removers
Varnishes and wood finishes can be toxic, especially the dust and fumes you will need to deal with when stripping.
You will therefore need to be cautious by following these tips:
- Protect the nearby area/surfaces by using drop cloths
- If removing varnish from the wooden floors, remove all the furniture outside the room
- Create cross-ventilation (by using fans and opening the windows) when working inside or take your project outside if possible
- When using solvents, chemical liquids, or gels, do not forget to wear long clothing, safety goggles, rubber gloves, and a respirator mask
- If possible, take off the hardware (like screws, knobs, hinges, etc) from the cabinet, doors, windows, or other furniture items you are removing varnish from
Tips for Choosing the Varnish Remover Product for Your Wood
Now that you are aware of the differences between each varnish remover let’s go over the choices you will have to make before you can make your full purchase.
These factors when considered will help you make your choice for the job you are planning to do.
1- Chemicals and Fumes
A long time ago most paint varnishes contained Methylene chloride which can give off very dangerous vapors and odors that can quickly fill your house for days.
Nowadays most producers are removing such harsh chemicals from the varnish removers and making them safer.
This allows you to use them indoors or anywhere else without worry, and some are even skin-safe now.
Allowing you to use it without having to worry about what may happen.
Although it’s always best to be at least a little careful when dealing with any of these chemicals as getting anything like this absorbed through your hands and inhaled in large quantities can possibly be harmful to you.
So even if a chemical says it’s safe for human skin contact it might still be best to wear gloves, eye, and respiratory protection.
2- How Effective It Is?
What’s more important by far though is how well it works.
If it is incredibly safe and does not work at the end of the day what’s the point?
Some are called fast-acting and can finish in as little as 2-5 minutes.
This may be what you want if you have a thinner finish or just a smaller job to get done quickly in a short span of time, as this will only get you results layer by layer rather than eating through a larger number of layers all at once.
Others do not as much, they can stay active for hours and eat away layer after layer of the varnish, this is best if you have multiple layers you need to get through as it will just not stop until it is done.
Even if it doesn’t eat all the layers the first time, you can always reapply it as well to get the intended result.
3- Where Can it Be Used?
Most varnish removers are multi-surface and can work on just about anything metal or wood.
They will melt and eat through plastics if left on though and should be watched carefully.
Better than watching though would be to find a varnish removed that names the specific type of surface you are trying to remove varnish from, especially if the surface is glass, fiberglass, or some other surface you want to protect.
Also, be sure that you get a finish that can be used on vertical surfaces if you intend to use it on any such surface as thinner products may not stay in the place you want them to.
4- How Much Time Should You Leave It On?
Different products require different things.
Some products say to leave them on for up to twenty-four hours but will gum up and harden if left on that long.
If it does gum up like this, it just makes your job harder to accomplish.
You should watch carefully if you apply a varnish remover that makes this claim as you don’t want to make the job any harder than it already is.
On the other hand, the thinner ones have a tendency to evaporate very quickly and won’t do much if it just has gone.
If that happens you should again be paying attention and be ready to apply the remover until the intended effect is accomplished.
Always be ready to reapply any finish remover you may be using if you don’t think it’s doing the job as well as you had hoped, just remove it the way you would normally and apply more.
5- How Much Cleanup and Preparations It Needs?
Before you start your project, be mindful of the safety and things you plan to do with the varnish remover.
You should always wear gloves and other protective equipment like a face mask when dealing with these chemicals.
Even if it claims to be skin safe or to not have any harsh chemicals in it, we have to remember what the job is, remove paint varnishes.
Chemicals, liquids, and stripping gels that aren’t harmful to humans can still be very dangerous when absorbed through the skin and into the bloodstream.
Even when working with odorless chemicals, goggles and a mask may be a good idea, just to air on the side of caution.
Just because the chemicals have no odor doesn’t mean they aren’t there anymore.
Also, always keep a rag nearby as well to wipe off the remover from anything you did not intend to get it on if that ever may occur.
Make sure the rag is moist and that there is some soap nearby to accompany it.
6- How Easy It Is at Wiping Off the Overall Finish?
After you let the product do its job and eat away at whatever it is, you’re trying to get rid of, it’s time to remove it.
Remember to be very gentle when wiping away.
And assuming the product you chose did its job correctly the first layers of the varnish should come off relatively easy, be ready to remove the later layers with steel wool or brush.
But remember that being gentle is key as we don’t want to mess up the surface underneath.
Gentle strokes with minimum pressure will get the job done.
And if those strokes don’t get the job done you can always reapply the finish remover or try a new one to that intended result.
If the first coat removes many layers but stops short, a second or third application may get you the results you wanted.
In the end, if you ask me – which of the above methods can remove varnish better from wood surfaces?
Is it scraping or sanding?
I would say both, and it would largely depend on the type of surface and varnish you are working with.
If you want to get the best results – try the combination of both.
Scraping is recommended for wood varieties like walnut, maple, mahogany, birch, and even plywood as it’s easier and safe.
So, what you can do is scrape the varnish first using some chemical strippers and then sand off the excess of it slowly that wasn’t removed.
This will ensure that you get finer results by stripping off old varnish from your old wood furniture without getting any damage.
Jack Luis is a semi-retired painter who loved painting his clients’ ideas on their walls.
He had worked as a painter for over a decade serving customers in areas such as Charleston, Mount Pleasant, Beaufort, and Georgetown, SC (South Carolina). Today in his free time, he likes to read and write about the newer techniques implemented in his profession. You may read more about him here or get in touch with him here.