Knots in Wood: What Are They and How Can You Use Them?

knot in wood

Anyone who has taken the time to observe wood has likely seen a knot in the wood. In fact, wood knots have even been mentioned in famous novels, such as Harper Lee’s To Kill a Mockingbird. Though some people might like to read about knotholes, most prefer to see their striking appearance on trees, boards, and other wooden parts.

What exactly is a wood knot, though? In this article, we are going to uncover just that. We also will learn why wood has knots, the different types of knots available, and how wood knots can be used by people. Read on to learn more.

What Is a Knot?

Simply put, a knot is a type of imperfection in the wood. Whenever knots are present in branches, the live wooden grain has to grow around the knot. Knots can be very beautiful, but they decrease the structural strength of the lumber too.

Whenever the tree is alive, the knot will most likely extend off the tree’s trunk. It will almost appear like the trunk is swollen in that location.

You can also see knots on different structures that are made from wood. These sorts of knots will be sanded down so that they are even with the rest of the wood, yet you will still see a texture and color difference between the knot grain and the other wood grain.

Causes of Wood Knots

Trees can have knots for a number of reasons. The most common cause for a wood knot is natural growth. As a tree grows, the lower branches naturally die so that the higher parts of the tree can get more nutrients. The growing tree simply grows around the dying branches, causing knots.

Another common reason why wood has knots is because of some type of damage to the tree. For example, fungal infections can cause black knot disease, which can cohabitate with some tree types and kill others.

The 3 Most Common Types of Wood Knots

To fully understand why a particular piece of wood has a knot, you have to understand the different types of knots. Yes, you read that right. There is more than one type of knot to be aware of. Here are the most prevalent types:

Encased Knot

An encased knot is the most basic type of knot. This sort of knot occurs whenever a branch dies and the tree continues to grow around it. As we mentioned above, this is the most common reason for a knot, making this the most common type of knot as well.

An encased knot will have a dark ring around it. This ring is the old bark from the dead branch. These sorts of knots are not very tight. Instead, they are sometimes called “loose knots” because the bark around them prevents the wood from binding tightly around them.

Intergrown Knot

An intergrown knot is found at the base of a living branch. These knots will be surrounded by circular growth rings, and they are often displayed in different architecture and creations for their visual interestingness. They do not have the dark ring as described with encased knots.

Spike Knot

Finally, the last knot we are going to look at is the spike knot. Spike knots occur whenever the board cuts through the branch’s length. Typically, it will have a tight base and a loose end.

Do Knots Damage the Tree?

Knots do not harm the tree directly, but they do negatively impact the wood’s strength. As a result, trees are much less sturdy where the knots are located. This surprises new wood enthusiasts since knots are notoriously difficult to cut through.

Even though the knots themselves can be difficult to cut through, the strength of the wood is affected because the knot disrupts the lumber’s grain. Whenever the grain is different, the wood doesn’t bind as strongly, resulting in weaker lumber.

As a result, most manufacturers today cut out knots before using lumber. Cutting out the knots helps to retain the structural integrity of the building in question.

Old Houses and Knots

Although cutting out knots is a common practice currently, this has not always been the case. Have you ever been to an old house that creaks? If so, you are most likely hearing the effects of knots being used in the structure.

As the building ages, imperfections in the wood eventually stretch out and crack, resulting in creaks and structural damage. Knots are the most common victims of this occurrence since the grains are not uniform.

How Are Wood Knots Used?

Even though most manufacturers do not use wood knots in their buildings, wood knots are used all the time. Because wood knots are so visually intriguing, they are often used in art, decor, and visual aspects of buildings.

Art and Decor

Many artists use wood knots in their work. Often, artists and designers will cut through the wood knot so that you can see through the center of it. The ununiform nature of wood knots makes this art more visually striking than non-blemished wood.

Knots in Buildings

Sometimes, buildings even use wood with knots, though they are not used for the structure of the building. Instead, the knots are typically displayed for aesthetic purposes. For example, they may be used in a nonvital wall, floor, door, or countertop.

All of these building parts are not necessary for the structure’s integrity, yet they allow you the visual benefits of the knot. Plus, these locations can easily be replaced if the knot cracks or creaks with time.

Tips for Using Wood with Knots

Using knots isn’t recommended for beginners because they can be difficult to work with. However, with the right tips, skills, and tools, you can easily use wood knots to add a little bit of drama and beauty to whatever item you are making. Here are some tips to keep in mind when working with knots:

Be Prepared

First and foremost, be prepared if you expect to use knots. You will need to use safety tools, such as goggles and gloves. Also, mentally prepare yourself. Knots are much more difficult to work with than regular wood. As a result, expect to need more patience and time to get the job done right.

Don’t Cut It Too Close

Anyone who has worked with wood before knows that it is better to overestimate than underestimate. After all, you can always cut away if needed, but you can’t add on wood after you’ve cut too close. This is especially true whenever you are working with the knot.

Many people who have never cut around a knot before cut the wood way too close. Even if the wood appears even with the healthy wood, the fibers may be too steep if they are located too close to the knot. For this reason, you really want to be generous when cutting around a knot.

By being generous, you don’t risk cutting it too close. If you do need to take some wood away, you can. However, you don’t run the risk of cutting grain that is too steep for the results you want.

Knock Out and Glue Knots Back In

Most people who use knots for visual purposes like to cut straight through the center of the knot. This allows the viewers to get the maximum drama from the knot. If this is what you want to do, you should knock it out and glue it back into place, especially if it is an encased knot.

You’ll want to use a dowel to pound out the encased knot. Make sure to be firm but not too harsh so that the knot does not break apart during its removal. Scrape off any loose bark that surrounds it.

With the excess bark removed, use an epoxy to glue it back into place. Epoxy is the only glue that will expand and keep the knot securely snug inside the other wood. The knock-out and glue method ensures that the visual features of your woodwork do not sacrifice its sturdiness.

Don’t Place Knots Close To Glue Lines

Because knots can seriously affect the integrity of your work, make sure to place knots away from the glue lines. The grain of the knot is different from the grain of the rest of the wood. If a glue line runs right through a knot, your table or another object will eventually get a crack in it.

To avoid this from occurring, make sure that the knot is far away from the glue line. This way, you don’t have any cracks in the structure, yet you still get the visual appeal of the knot itself.

Final Thoughts

Even though knots are technically an imperfection of the wood, they can be very attractive and striking on the right structure. Artists and architects especially like using knots so as to increase the visual appeal of whatever item they are making. However, knots decrease the strength of the lumber, which is why they should be cut out and not used in frames or other vital structures.


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Timberland Enthusiast Jan 1977 – Present Columbia, South Carolina Since graduating from law school I have worked in various capacities within the real estate, timber management, lumber production and pine straw harvesting markets in South Carolina. Newmark Grubb Wilson Kibler May 2016 – Dec 2020 Columbia, South Carolina Det Bowers joined Newmark Grubb Wilson Kibler in May of 2016. Prior to joining Wilson Kibler, Mr. Bowers served as a licensed attorney practicing in Federal, State and Municipal Courts. Other business involvements have included real estate development, retail development and operations, agribusiness, forestry products, outdoor advertising and insurance.

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