How to Seal Wood

  • December 8, 2019
  • / By Dale Keese
Deck with a Sea View

You have been working on a wood project for several weeks now and it is coming to an end. You have poured hours and hours of sweat and tears on weekends in your backyard and are finally proud of your handiwork. But even after so many weeks of toiling, you feel something is lacking.

Deck with a Sea View

Slowly, it dawns upon you that you have done all the rough work, but have left the finishing for later. A wood finish will not only make it appear richer and deeper but also forms a sort of film on the surface that seals the wood.

Essentially, the pores of the wood are sealed and stained, giving it a smoother, more even look and feel, and also protects it from the elements. If this is not the first time you have worked with wood, you would probably know the importance of the processes of sealing the wood and staining it. However, a lot of people are confused between the two processes and often confuse them for one another.

While one process (staining) will enhance the look and feel of the wood, sealing will protect the wood from rotting and other elements. Let us quickly clarify how different these two processes are once and for all.

  • Sealers are applied to the outside of the wood and its main purpose is to repel moisture and make it waterproof. This is done because moisture in the wood can lead to rotting and fungal growth.
  • Sealers have limited anti-ultraviolet ray protection, so the color of the wood can turn to gray and fade, leading to splitting and cracking.
  • Sealers can be applied to any wood surface and can be applied using a paintbrush.
  • Sealers need reapplication from time to time but are easy to apply. They do not need much expertise and may need to be reapplied every year, depending on the quality of the sealer.


  • Stainers, on the other hand, go deep inside the wood, unlike sealers that are applied to the surface.
  • They can change the color of the wood because they contain pigments.
  • Apart from some water-repelling qualities, they also protect against UV rays and are available in opaque, transparent or semi-transparent variants.
  • They are more expensive than wood sealers but can last much, much longer.

However, there are products available on the market known as stainer-sealer combos, which will do both jobs in a few coats. Now that we have established the differences between the two, we can continue our article about wood sealing.

No matter what your purpose of sealing the wood is, you want it to last a long time and hence you need to do it properly. Wood sealers can be put into two categories; acrylic or water-based or solvent and oil-based. Let us take a look at these.

Oil-Based vs Water-Based Wood Sealers

The most common question when someone suggests any of these two sealers is: What is the difference? In effect, both of these sealers act as an extra layer on the wood, protecting it from damage and elements. Remember that these layers are not permanent and will show signs of wear over time.

Standing in the Rain

The commonly-sold sealers are made up of polyurethane, which is plastic. It is also available in a lot of varieties such as satin or glossy. It is mostly used for side tables, bookcases or tables, and desks, that is to say, anything that is to be used indoors.

Let’s look at both these sealers based on their properties.

  • Color: A water-based sealer has a clear hue, while an oil-based sealer will be slightly amber. The water-based sealer will retain its clarity over time (meaning it will not cloud or color), while the oil-based sealer will turn darker and will continue to do so.
  • Durability: This is something that has been a topic of debate for hardware store owners. Both types of sealers vary somewhat when it comes to durability, but if good-quality products are used, this difference is barely noticeable. The misconception is that water-based sealers are “weaker”, but it has been proven several times that if applied properly and taken care of, these can last as long as oil-based sealers.
  • Odor: You will barely notice when a water-based sealer is being applied in the house. It has no smell, and you would not need to wear a respirator. You and/or your pets can remain in the house while a water-based sealer is being applied. On the other hand, an oil-based sealer has a caustic smell that seeps into your clothes and clings on to you for hours. You would need to wear a respirator while applying an oil-based sealer. Also, it would be ideal for the house to be vacant for the same purpose.
  • Heat-Resistance: Water-based sealants (save a few exceptions) are generally used for wood structures that are not exposed to extremes. They cannot handle heat or chemicals well. Oil-based sealants have better resistance to heat and hence can be used on kitchen tables.
  • Texture: With an oil-based sealer, two coats are all you need but they tend to develop dents since it is soft in density. A water-based sealer is a harder coat but needs 3-4 coats, depending on the surface and the quality of the sealer. Usually, experts use 3 coats of the sealer, regardless if it is water or oil-based.
  • Time to Dry: You can apply many coats of a water-based sealer in a day, usually 3-4 coats in the same day because it tends to dry faster, in say, about 4-6 hours. On the other hand, an oil-based sealer usually can only be applied once a day because of its thicker consistency, and hence, needs a longer time frame to dry.
  • Cost: Oil-based sealers are usually cheaper and you can get a 5-gallon can for about $120-150, whereas a water-based sealer would cost upwards of $200 for the same amount.

While talking about sealing or finishing woodwork, you may have come across terms such as lacquer, varnish, shellac, and polyurethane. Though these names are used in the same vein, they have different uses. The common factor between them is that they all make for excellent sealants.

Experts will tell you that there are countless ways to seal the wood. But they also say it is not as straightforward as just picking up a product and following instructions (though a majority of people do that).  If we dig deeper, we will find that different kinds of materials can be used on different types of wood. Let’s take a look at these.

Minimalist Furniture


This is one of the most widely-used products used for sealing and finishing because of the gloss it leaves behind. It adds a warm, amber color to wood and is thinner than other finishes which we will discuss in brief. Usually, one coat of lacquer is sufficient. Lacquer is made up of plant or synthetic resin which is dissolved in alcohol and is available in a variety of sheen.

One of the reasons it is such a popular choice is because it dries fast; say in about 15-30 minutes and is scratch resistant. But one of its drawbacks is that it tends to turn yellow over time which could be unwanted if the wood it is being applied to is light in color.

It can be either sprayed on or can be applied using a brush, but be warned, it emits strong fumes, so open up windows and keep the room well ventilated before you go to work.


Shellac is a natural product that has been in use for a long time. It is made from the secretion of an insect that is typical to Southeast Asia (specifically India and Thailand), which is scraped from wood bark and the flakes are treated with alcohol. Applying this on wood not only gives it a protective layer, but also adds an amber color.

One of its major drawbacks is that it is not heat resistant, and will crack or flake if exposed to intense heat. Shellac can be applied using methods of padding or using a brush.

Shellac dries pretty fast, from 30-60 minutes, which means you can also touch-up if you feel your handiwork is lacking at any time. Shellac blends in with most types of wood shades easily. Shellac is used with woodwork and trim most of the time.

Applying Varnish


The varnish is another popular material that is not only used with wood but also other surfaces. It is generally used as a topcoat for a shiny finish and can be used for outdoor projects because it solidifies into a hard shell and resists yellowing. Also, it provides UV protection.

All in all, the varnish is a great all-round, easily available and popular choice because of its wide usage and handling almost any kind of environment. They don’t have a very hard finish, which means they can withstand any sudden changes in the temperature. You should not apply it on old-look furniture though since varnish tends to look "plastic-y", which may ruin the desired effect.

They are usually available in clear or lightly-colored finishes and some variants are known to discourage the formation of mold or algae. For this reason, varnish can be used on outdoor projects which have proximity to water, such as beach chairs, boats and so on.

Applying varnish is easy; just take care and never shake the container too vigorously before use, as many before you have found out to their dismay that shaking the container leaves too many bubbles inside, causing cracks in the finish after drying.

You may find upon opening a varnish container that it already had formed bubbles. This can be easily rectified by thinning it a little using mineral spirit and stirring it gently. This will make the varnish easy to apply on most surfaces.

Creating Your Own

You can make your solution by mixing turpentine oil (it has a rather strong smell) and varnish. This simple solution is versatile; the oil penetrates the surface of the wood and the varnish does what it is supposed to do. It is a win-win solution if you are feeling adventurous, and you don’t need any special equipment to do that.

All you need is a clean cotton cloth and work over the desired area. It spreads easily and smoothly and dries off fast enough for you to put in more coats. You don’t need to worry about if you find you have put excessive solution; you can just wipe it off with another clean cloth and let it dry.

Sealing Wood

Now that you know the differences between oil and water-based sealers, we trust you will make an informed decision when it comes to sealing your wood projects. Which brings us to the main event; that is how to seal the wood. And we will get right to it.

In this short tutorial, we will assume that you have already decided on a sealer that is suitable for your requirement, whether it is a water or oil-based sealer. Though if the surface you are going to use it on is of a lighter shade, we recommend that you use a water-based sealer because it is colorless and will enhance the natural look and feel of wood. Unless you want to make the surface look very glossy, avoid an oil-based sealer.

Also, make sure that the sealer will also limit dirt build-up and protects against UV rays. Also, while selecting your sealers, you should always read the instructions on the back of the sealer’s container to see if the manufacturer has advised any safety gear. Regardless, if you are doing this at home, you should always wear safety gear such as thick rubber gloves and a mask, to protect your skin and from inhaling toxins.

Living Room

Required Materials

  • A high-grade oil and water-based sealer of your choice
  • A brush with natural bristles
  • A few pieces of wood
  • Sandpaper (different grit varieties, from 100 to 400)
  • A small bucket (to use with the sealer)


  1. 1
    We are assuming that the surface that you want to seal has recently been painted. Let us assume that it is a chair. If so, then you have to make sure that the paint has completely dried off and that it is not sticky to the touch. If it is so, you will need to set it aside and let it dry completely.
  2. 2
    If you are using a water-based sealer, don’t stir it too vigorously when you pour it into the bucket. Doing so will create bubbles under the surface of the sealer and will stick to the brush when you put it in. These bubbles will prevent a smooth application of the sealer, and hence you should avoid their formation. Be gentle with the brush and squeeze out the excess sealer back into the bucket.
  3. 3
    For the same reason, do not shake the container vigorously (for whatever reason).
  4. 4
    Apply long, slow, even strokes. Start from the middle and work your way to the edges.  If you think you have left out some of the areas, don’t worry and let the sealer dry off first to cover it in the second pass. Do not paint over the wet sealer immediately. This is applicable to both water and oil-based sealers.
  5. 5
    Don’t go overboard with the layering or coats. Too many layers or over-enthusiastic strokes will spell disaster for this project. That effort can look apparent and hasty.
  6. 6
    Let the sealer dry completely and try not touching it. You can check after a few hours (just to be on the safer side) and if it does not feel wet, it is ready to use.

Now let’s move on to bigger subjects and find out how you can go about waterproofing a deck.

How to Seal a Deck

If you happen to have a wooden deck, you are probably aware that it is a great asset to any home. But you are also probably aware that wooden decks would require proper and constant care. Taking care of it would ensure that the deck has a longer lifespan and looks as good as it did on the first day.

If the deck is new, experts suggest that the deck should be left to weather and dry for as long as 3-9 months. When you think you are ready to seal the deck, you should get to work.

Working on Wood Floors

Cleaning the Deck

First off, the deck needs to be cleared of all gunk and sediments that have settled in. You can go about it in many ways; if you have a small deck, you can get this accomplished the old-fashioned way, by getting on your knees and sanding out the rough parts thoroughly. You can sweep it thoroughly afterward, before applying a deck cleaner (completely optional).

Another efficient way to do this is by using a pressure hose (don’t set this to very high because you may end up damaging your deck). We are assuming that you have cleared the deck of all the equipment and chairs for this purpose. Go over the deck thoroughly with the hose and wash away anything that has attached itself to the deck over time, such as debris and mud.

Once you are satisfied that the hose has done its job, use a palm sander to smooth away all the rough edges, splinters or kinks that may have developed. You can read more tips on cleaning your deck in this detailed article.

If you are not satisfied with this, you may want to follow it up with a deck cleaner. These are readily available on the market. You can even make your own with available materials in the house. Here is how:

  1. 1
    You will need a bucket that can accommodate a regular broom or, ideally, a deck broom’s head. Fill the bucket halfway with warm water and add 2.5 cups of oxygen bleach. Avoid chlorine bleach because it can be harsh on deck boards and cause discoloration.
  2. 2
    Stir until the powder dissolves and disappears. Add ½ cup of mild liquid dishwashing soap and stir and let it sit for a bit.
  3. 3
    You may want to cover any shrubs or plants using clear plastic sheets before you clean the deck. Though the solution you have made is pretty mild, you should still take preventive measures.
  4. 4
    You can either use the broom or a paint roller to apply this solution to your deck generously. What you will be doing is saturate the deck with this solution and letting it get in the spots that are difficult to get to. Work the broom or the roller to work up a little lather too and work your way from one corner of the deck to the other.
  5. 5
    Once you have cleaned the deck to your satisfaction, leave the solution on for up to 15 minutes. If you have used a commercial product, follow the instructions at the back of the container.
  6. 6
    Rinse the deck with the garden hose, albeit, with less pressure. The deck needs to be completely dry before you start sealing it. This may take up to 72 hours depending upon the weather.
Food Styling

Working with the Deck Sealer

There are several sealing products available on the market (for this specific purpose) at online or hardware stores. Prices vary from $30-$45 per gallon. Most of these are versatile products that can be applied to a variety of wooden structures such as patios and fences as well. They are either water or oil-based or made up of natural ingredients.

Most of these have UV blocking or waterproofing qualities and are available in transparent or opaque formulas. Choose the one which retains the natural color of your deck.

Since you have already cleaned and sanded your deck you don’t need to do any more preparation, though a final sweep after it is dry could go a long way as you may come across loose screws or exposed nails. What you should do though, is check the weather forecast and choose days with moderate weather. Let’s start sealing the deck:

  1. 1
    You may need to protect your siding or railings, so you may want to tape them off with masking tape or painter’s tape so as not to get the sealer on them.
  2. 2
    Use a bristle brush to apply the sealer thoroughly across the surface of the deck. You can use an alternative applicator such as a roller, but a bristle brush is much more effective since you can go between the boards.
  3. 3
    Work in strokes, covering 3-4 boards in one go. Work carefully, and try not to drip the sealer too much on the boards since the splotches will stand out and will be difficult to get rid of.
  4. 4
    Be thorough and be patient, because this may take a while. Follow the manufacturer’s instructions; you may need to do this twice, but not more than that.

Now that you know how to seal and waterproof wooden structures, here are some tips with regards to how you can keep them looking good and protect your investment.

Atrium with Hammock

Tips for Maintenance

  • Seal Regularly: Whatever you are using the sealant on, make sure to apply it at least once every two years. Remember that wood is nature’s product and hence, is vulnerable to temperature changes, moisture, and UV rays. Sealing becomes all the more important if the wooden structure is outdoors, such as lawn chairs or a deck. Sealing will add more years to the wood and you will need to use a good penetrating sealer with it.
  • Clean Regularly: You will not want dust to settle on your wood furniture or deck. Clean away the dust particles and any other impurities as regularly as you can. A daily wipe is recommended but once in 2 to 3 days will also do. This will save you on future work.
  • Clean Stains: If you have stubborn stains on your furniture, you need to clean them off before you set about sealing it. You can make a simple oxygen bleach paste to tackle it. Just mix 1½ teaspoons of bleach in a quarter bowl of water until the consistency is paste-like. Apply this paste on the stains and leave it on for 15 to 30 minutes. Rinse it off and repeat if necessary. Sealing over stains will make them difficult to get rid of later.
  • Avoid Paint: Some guides will tell you to paint over your furniture or deck with paint. This is a lazy practice and would spell disaster later. Eventually, the pain will start to bubble, crack and peel off under harsh conditions, which means you will have to keep repainting every season. On the other hand, oil-based sealers fade naturally and are not harsh on the wood.
  • Don’t Let Moisture Settle: Take care of outdoor wood structures and furniture. If you live in an area that sees a lot of snow, you should be shoveling it at the first opportunity you get. The same goes for indoor furniture. Avoid spillage, but if it happens, wipe it off immediately. Not doing so will trap the moisture in over time.


This concludes this extensive guide on sealing and waterproofing wood. You can now identify the various sealants and their usage. In most cases, a good quality sealant will do the job, but remember to do it every two years or so and do not ignore regular maintenance. We hope that you found this article helpful and will help you tackle sealing jobs around the house.