Did you just set up a fabulous wooden vanity in your bathroom? Has the contractor just laid down your gorgeous hardwood floors? No matter what it is, having wood elements in the bathroom gives off a sense of luxury and comfort at the same time.

But even though it might look stunning, unless you take good care of it, the wood in your bathroom can warp or even rot. So, how can you waterproof wood so that it stays beautiful for a long time? Well, let’s find out.

Waterproof Your Wooden Furniture with Oils

Using oil to waterproof wooden furniture is extremely popular because it’s cheap and somewhat easy to do. Now, there are a couple of different oils you could use to get the job done, but I recommend using tung oil.

Tung Oil

No matter what kind of wood you have in your bathroom, tung oil will do the trick. In fact, you can also use tung oil to finish metal, concrete, and brick surfaces. A gallon of tung oil can cover around 400 square feet of wood, but keep in mind that you need to apply at least four coats.

Unlike some of the other coats we’ll be talking about, tung oil won’t just form a layer over the varnish. It will get absorbed into the wood, creating a long-lasting, waterproof barrier. But even though it makes the seal more durable, tung oil also has a longer drying time.

Depending on the type of wood you are coating, tung oil can cure for 7 to 14 days. Also, that time will vary based on how many layers you’ve done.

But if you can’t wait that long, you can put a thinning agent into the oil and significantly cut the drying time. The one downside to this method is that you can only do it for the first coat. If you do it more than once, the oil won’t fully penetrate the wood.

Applying Tung Oil

Before you can go in with tung oil, you need to prep your wood. First, start by cleaning the surface you want to cover, making sure there’s no dirt, debris, or dust on it. Also, if you’re repurposing and reusing wood, it might already have a protective coat, which you have to sand down.

I recommend using a fine-grit paper, so you don’t accidentally damage the wood underneath. Once you’ve sanded everything, clean the surface one more time before you get to work.

You can also thin your oil using a solvent or mineral spirits. By thinning the tung oil, it will penetrate the surface better and dry faster. But I don’t recommend thinning it if you’re working with unfinished or weathered wood.

Linseed Oil

Linseed oil is a somewhat inferior choice compared to tung oil because it has a longer curing time. But if you’re in a pinch and can’t buy tung oil, boiled linseed will do the trick. It has the same preparation process and you can use a thinning agent to shorten the drying time.

If you do decide to go with linseed oil, you’ll be happy to know that it is totally water-resistant and gives a nice, glossy finish. You can also get it in different colors and finishes at most home improvement stores.

Waterproofing Wood with Polyester Resin and Acetone

If you want to waterproof your wood with polyester resin, you’ll get to choose between a laminating and finishing one. You should use the laminating resin if you want to paint over the seal.

But in case you want to keep that warm look of the wood intact, I recommend using a finishing resin. It is basically the same thing as the laminating one, only it has wax in it so it can fully harden.

Personally, I prefer using a polyester resin instead of oil, simply because it has a much shorter drying time. What’s more, you can also use it to refurbish rotten and damaged wood, as well as waterproof fiberglass.

Applying a Polyester Resin and Acetone

Again, before you can go in with your sealant, you need to prep your surface. If you’re working with weathered wood, use fine-grit sandpaper to get rid of any imperfections. Clean the surface well before you start applying the coats.

You have to mix the resin and acetone together to create your finish. You can pour some resin in a bucket and slowly start adding the acetone in until you get a consistency that’s a bit thicker than water.

Keep in mind that you’ll need to make a new mixture for each coat, so don’t go overboard the first time. Also, when you’re making new batches, put less acetone in to avoid diluting the mixture too much.

If you’re coating a smaller wooden surface, like a vanity, I recommend using a soft-bristled paintbrush. But if you’re working on your floors, you can use a paint roller for easier application. Just make sure you’re cleaning the brush and roller with acetone before you go in to put another coat.

For the best results, I recommend finishing your wood at least five times, making sure you wait for 20–30 minutes between each coat. In your final mixture, you can add a couple of drops of liquid wax for a high-shine effect. You should leave the wood to cure for four to six hours before you can start using it.

Waterproofing Bathroom Furniture with Sealants

Sealants are a tried-and-true method of waterproofing your wood that won’t break the bank. There are three types you can choose from:

  • Varnish
  • Lacquer
  • Polyurethane sealant

You can either brush or spray them onto the wood and they usually have pretty short drying times. But I would recommend using a sealant only if you can work in a humidity-controlled environment.

Also, never shake or stir any of these sealants because doing so can create air bubbles. The bubbles will stay on the surface of the wood even after the sealant has dried.


The varnish is basically a mixture of resin, solvent, and drying oil that will give your wood a nice, thick finish. It won’t turn yellow over time and it will make your wood more durable. For your bathroom, I recommend using a spar varnish, just because it creates a good water barrier.

You can also use a varnish spray for the furniture in your bathroom, like cabinets and vanities. It’s easy to use and only takes about 15 minutes to dry.


Lacquer is a mixture of dissolved resin in an alcohol solution. You can get it in a wide variety of finishes and thin it out if you want it to dry faster. But since it can develop a yellow tinge, I recommend using lacquer only on darker, deep-toned wood.

One thing to keep in mind is that lacquer can emit some really strong and potentially toxic fumes. If you can, either use it outside and then bring the furniture in or at least make sure you’re working in a well-ventilated room.

Polyurethane Sealant

Last up is a polyurethane sealant that can give your wood a gorgeous glossy finish or even a soft and gentle sheen. It is a mixture of acrylic and polyurethane resins, as well as different solvents.

It’s easy to use and clean up, and since it won’t turn yellow over time, you can use it on light-toned wood. Even though oil-based polyurethane sealant is a bit trickier to clean compared to water-based one, it is much more durable and long-lasting.

Preparing the Wood

No matter which product you end up using in the end, you first need to prep your wood. First, as I mentioned, you need to sand down your wood starting with 180-grit sandpaper. During this step, it’s really important that you remove any imperfections, seals, or paint that’s on your wood.

Then, to ensure a smooth finish, use a 220-grit paper. When you’re happy with how the wood’s looking, vacuum and clean your area, making sure there’s no debris or dust around. Also, I recommend cleaning your wood with a damp towel or cloth and waiting for it to dry before you start coating. 

If you decided to go with oils, you can work them into the wood using your hands or a lint-free cloth. Rub the oil into the wood, making sure there aren’t any puddles left. After 30 minutes, you can go over the surface with a clean, dry cloth. For best results, repeat this step a few times.

On the other hand, if you’re using a sealant or polyester resin, you need to work with a brush. You can put certain sealants in a spray bottle for easier application. But check the manufacturer’s instructions and guidelines first, because it doesn’t work for every product.

Final Thoughts on Waterproofing Wood for Bathrooms

Waterproofing furniture and floors for your bathroom can be a pretty challenging but rewarding task. How much time and money you spend on this project will all come down to what you want to use.

Even though oils are pretty cheap, I wouldn’t recommend using them for your floors because they have such long drying times. But if you need to cover a big surface and do it fast, going for a sealant might be your best choice.

No matter what you end up using, it’s all about taking your time and coating in thin and even layers. Also, never paint another coat while the previous one is still drying. Most importantly, work in well-ventilated rooms and wear proper clothes and safety gear.

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