Is Walnut Wood Water Resistant (A Clear Answer) - Thumbnail

Is Walnut Wood Water Resistant (A Clear Answer)

Walnut wood is a lovely shade of brown that can brighten up any project. This is one of the reasons why this sort of wood is so popular. However, before you start making something with this wood, you should consider how it reacts to moisture, especially if you plan to make furniture in a damp place like a bathroom. So you want to know, is walnut wood water resistant?

In short, due to its hardness and medium durability class, walnut wood has reasonably strong water resistance. As a result, when exposed to water, walnut wood resists shrinkage, warping, and rotting.

This article discusses how moisture is absorbed by the wood, what consequences this can have, and how you can make wood even more resistant to moisture to give you a better understanding of the water resistance of walnut wood.

How does wood absorb water

To understand how wood absorbs moisture, it’s helpful to know how the wood you’re working with was while it was still a tree.

You should think of wood as a conduit for water and nutrients that are received by the tree’s roots and must be transported to the leaves.

The wood includes very small cells that allow this to happen. These cells have thin walls and can communicate with one another by passing moisture and nutrients through them. Water can be transferred from the roots to the leaves in this manner, from cell to cell.

A cell can therefore release water, which happens when we start drying the wood and the cell becomes empty (and also shrinks, depending on the type of wood). The opposite is also possible, so if moisture gets on the dry wood, the cells can store the water again, resulting in expansion.

Wood is hygroscopic, meaning that like a sponge, its moisture content changes depending on the relative humidity of the surrounding air. When the humidity increases, the wood absorbs moisture from the air and when the humidity decreases, the wood releases water into the air.

So if you are wondering, is walnut wood water resistant, then you will understand that walnut and any other type of wood is sensitive to moisture. However, not all types of wood are equally sensitive to this. Moisture absorption is largely determined by the hardness of the wood, which is expressed in Janka rating. If you want to learn more about this, I recommend reading my article, What Is Janka Rating And Is It Still Relevant.

How does water affect wood

Water can have a variety of effects on wood, ranging from mild to severe. As previously said, this is dependent on the sort of wood. Each type of wood has a distinct hardness, which affects the wood’s long-term endurance. More information on sustainability may be found in my article A Clear Guide To Wood Durability Classes + Chart.

Before we answer the question, is walnut wood water resistant, it’s important to understand what water can do to wood. This allows you to determine whether walnut wood is the ideal choice for the project you’re working on even more accurately.

Wood expands as it comes into touch with water because the cells fill with water. This isn’t a problem for some projects, but it might have severe repercussions for others, such as cupboard doors that won’t open or wood cracking.

Mold growth, which leads to deterioration, is a more serious issue. As a result, the rotting wood will weaken and fall apart over time. There are, however, other varieties of wood rot, which I shall discuss later in this essay.

If you read the above, you probably now realize that wood that absorbs water can cost you a lot of money to restore. Water damage can be the result of a wide variety of things. It can be the result of high humidity or direct contact with water.

It is therefore good to start using the right type of wood for the purpose you have in mind. If you want to use walnut in a room where there is moisture, or if water will come into direct contact, it is good to know to what extent walnut wood is waterproof.

What causes wood rot?

Wood rot is a type of degradation brought on by a mix of moisture and fungi (microscopic organisms). Fungi cannot grow on dried wood, hence the wood must be kept moist at all times for them to establish themselves.

While there are certain fungi that are beneficial, such as mushrooms, others are harmful.
In nature, fungi are the clearers of fallen wood. However, when we make something with wood, we always want to prevent these fungi from destroying our project.The many species that cause wood rot are divided into three categories based on their impact on wood.

Brown rot

Because the wood’s surface seems to be dry, brown rot is sometimes known as “dry rot.” Brown rot fungi feed on the cellulose that makes up the structure of wood. When the cellulose in the wood breaks down, it shrinks, turning a dark brown hue and shattering into small cube-shaped pieces. This type of fracture is known as a cuboidal fracture.

Brown rot flourishes in temperatures ranging from 18 °C to 32 °C (65 °F to 90 °F), and it spreads quickly once it starts to grow.

Is walnut wood water resistant - Brown rot
Is walnut wood water resistant – Brown rot (source: Wikipedia)

White Rot

White rot appears when wood turns a whitish or light yellow color and feels spongy. White-rot fungi break down lignin, another component of the wood structure, leaving the light-colored cellulose left, while brown rot fungi attack cellulose. White rot, like brown rot, occurs at temperatures ranging from 18 to 32 degrees Celsius (65 and 90 degrees Fahrenheit).

Is walnut wood water resistant - White rot
Is walnut wood water resistantWhite rot (Source: Wikipedia)

Soft rot

Soft rot fungi destroy wood more slowly than brown rot and white rot fungi, but they flourish in temperatures between -17 °C and 45 °C, which are too hot and too cold for the other species to live (0 and 110 degrees Fahrenheit). Although it is most usually seen in fallen logs and trees, soft rot fungus chews down cellulose, giving the wood a honeycomb look.
Related: how to prevent mold on wood – a quick guide. Check this article if you want to keep mold away from your projects.

Is walnut wood water resistant

And now the question of this article is, is walnut wood water resistant?
Due to its hardness and durability class 3, walnut wood is resistant to wet conditions and water drops. As a result, walnut wood resists shrinkage, warping, rotting, and other disasters pretty well when exposed to water.

However, because there is always the potential of wood-decaying or working, a decent finish is required. If you make sure it’s handled properly, you can raise the water resistance of walnut wood. Like that, you can avoid problems.

Wood finishing can be done in several ways. You can use an oil, wax, stain, or varnish for this. Which choice you have to make depends on your own goal, but also on the use of the object you are making. To discover more about wood finishes, I suggest you take a look at my article, 4 Types Of Wood Finishes. What To Use When And How?

In some cases, wood will come into contact with food. Then it is good to look for food-safe finishers. You do not want your food to be contaminated with toxic substances from the finishing layer. These can cause chronic poisoning.

Walnut is a sturdy and easy-to-work-with wood with a fine texture. It’s a common choice for furniture, wall panels, and cabinets because of this. Walnut offers a lot of benefits, but it’s also a very pricey wood. You may read more about why walnut wood is so expensive in my essay Why Is Walnut Wood So Expensive. So, before you begin, consider whether walnut is a suitable material for your project.


Walnut wood contains Juglone, a poisonous chemical that can cause long-term harm to humans. Because not only the sawdust, but also the wood itself, contains juglone, it is not advised for use as a type of wood for making products that come into touch with foodstuffs. I wrote an article about it here: Is Walnut Wood Toxic, Important health info.

Is walnut wood weather resistant

Walnut has great weather resistance because of its hardness and durability class 3. Untreated walnut wood can have an outdoor life of up to 15 years.

Walnut wood comes in different variants. For example, there is black walnut, butternut, or English walnut to name but a few. Each variant has a different hardness and durability.

On the website wood database, you can compare all types of walnut and make the best choice of which walnut wood is best suited for the project you are working on.
If you want to compare walnut with oak, I can recommend you to check out my article, Walnut vs Oak, a quick guide to help you choose.

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