How to Prevent Wood from Warping

Wood is one of the most commonly used and versatile building materials all over the world. But it certainly doesn’t mean that wood doesn’t have drawbacks.

One of the most troublesome and frustrating problems of working with wood is warping. Not only does it destroy the beautiful look of wood but it can also decrease its longevity.

That’s why I have compiled this guide that contains the best ways to prevent the wood from warping.

Wood Warping Types

The following are five different types of wood warping that you should know. 

Bow

In this warping type, the wood bends upwards or downwards on both ends and makes a shape of a bow. It usually happens when the middle part of a wood board is thicker than the ends.

Wind

The wood creates a twisted shape by turning at both ends and turns into a shape that looks similar to a twisted ribbon. It usually happens because of varying fiber orientation angles in a wood board. 

Kink

The kink warp takes place when a piece of wood bends upwards or downwards on one end. It happens when one end of the wood board absorbs or loses moisture faster than the other. 

Crook

It takes place when one edge of the wood piece is exposed to moisture. As a result, it starts looking like the letter “C”.

Cup

The cup warping happens when both the edges of the wood piece curve outward or inward. It happens when one face of the wood piece loses or absorbs more moisture than the other.

How to Prevent Wood from Warping

If you have ever spilled water on a piece of paper mistakenly, you’d already know that it becomes uneven and wrinkled after drying. The same concept happens to wood when it warps.

It means that moisture is the biggest culprit behind wood warping. There are some other factors such as grain direction and wood species that contribute to warping. However, these factors won’t affect your wood if you control air humidity and wood moisture successfully.

The following are some of the best ways that will allow you to deal with moisture to prevent the wood from warping.

1. Choose the Correct Wood Type

You want to choose the species of wood that’s most compatible with the humidity levels of your area. It’ll be less prone to warping because it would have already achieved its EMC.

The EMC or Equilibrium Moisture Content refers to the condition when a piece of wood neither takes nor loses moisture. It means that the wood has similar moisture levels to its surrounding air.

Pre-Treated Wood

We recommend you buy kiln-dried wood from a local lumber yard. Kiln drying is a complex process in which the wood is dried at high pressure and temperature. In addition, it’s also exposed to different chemicals that make it more resistant to absorbing or losing moisture.

Wood Species

There are some wood species that are naturally resistant to warping and shrinking. Hardwood species such as Redwood, American cherry, and oak have less tendency to warp even in highly humid environments. These wood species also have some natural acids and oils that keep them from absorbing moisture from the air. 

Whereas softwood species such as balsa warp very easily. They usually have high moisture content and are not as dense as hardwood species. That’s why they are prone to warping as they lose their moisture content.

Wood Grain

Keep in mind that wood with an open grain has a high tendency to warp as compared to wood with close grain. It happens because of the natural spacing between the wood fibers. The larger the space the higher the risk of warping.

Again, choosing hardwood is your best bet as they come with closer grain or less fiber spacing than softwood species.

Wood Cut Type

The warping tendency of the wood board also depends on its cut type. It means that two boards cut from a single tree can lose or absorb moisture at different rates. 

A wood board cut from the center of the tree will be highly resistant to warping because it’ll have extremely dense grain.

It also means that a hardwood board will warp easily if it’s cut from the outer part of a tree. Whereas, even a softwood board will resist warping if it’s cut from the heartwood. Therefore, you’ll also need to pay attention to cut type while choosing wood for your project.

2. Stain the Wood

Staining your wood is one of the most effective ways to prevent it from warping. A thick coat of a high-quality stain keeps the wood from losing or absorbing moisture from the surrounding air. It works as a blanket to eliminate the effects of changing humidity levels on the wood.

This method especially comes in handy if you need to transfer wood from one place to another with different humidity levels.

Applying Stain

You can apply the stain to your wood using the following steps:

1. Place your wood board on a flat and sturdy surface.
2. Damp a piece of cloth and dip it in the stain.
3. Start applying the stain by moving the cloth on the wood in the grain direction.
4. Use a dry cloth to remove the excess stain and let the wood dry.

You’ll need to use these steps multiple times to apply multiple coats for better results. However, you can also apply a sealant over a single stain coat using a wall paintbrush to make the process easy.

If you have wood in bulk and don’t have enough time, consider using the method discussed above to stain only the ends of the board. That’s because the wood loses or absorbs moisture 15 times faster from its ends as compared to other surfaces. So, staining the ends of your wood boards will allow them to dry evenly and avoid warping.

3. Adjust Humidity Levels

It’s important to maintain the humidity levels of the area where you store your wood. Higher or lower humidity levels in the air than wood moisture content will lead to warping. It’s important to note that the moisture content in the wood will not always be equal to the humidity level in the air.

For example, a piece of wood will acquire about 30 percent EMC in a place with 100 percent humidity. Whereas, a wood piece will reach zero EMC in a place with 0 percent humidity. 

Use the following table to understand the wood equilibrium moisture content with respect to air humidity at a temperature ranging from 30 to 100 Degrees Fahrenheit.

You’ll need to check the moisture content of your wood and the humidity level of the air to make necessary adjustments.

Checking Wood Moisture Content

The most effective and easiest way to check the wood moisture content is to use a moisture meter. It’s a great tool that comes with two prongs that you need to insert into the wood.

Then you’ll need to wait for about a minute to let the moisture meter calculate the wood moisture content. After that, it’ll show the calculations on its display.

Make sure that you take multiple readings and average them out because each result can vary by one or two percent. The average of multiple results will allow you to get as close to the actual wood moisture content as possible.

Checking Humidity Level of Storage Area

You can use a hygrometer to determine the humidity level of the storage area. I recommend you use a digital hygrometer because you only need to turn it on and place it about one meter high from the ground. 

The display of the digital tool will show you the current humidity level of the place within a couple of minutes.

When Humidity Level Is Higher

If the humidity level is higher than it’s supposed to be with respect to the wood moisture content, you’ll need to lower it down. The best way to decrease the humidity level of your storage area is to use a dehumidifier. 

It’ll keep the wood from absorbing moisture from the air to prevent it from warping.

When the Wood Moisture Content is Higher

The moisture content of wood can also be higher than its expected value with respect to the humidity level of the air. In such a case, you can place your wood stacks under direct sunlight so that they can come to EMC. 

You can also kiln-dry them for faster drying if you have the equipment. 

Make sure that you place your wood boards on a perfectly flat surface to make a stack. This way the boards at the bottom will be properly weighed down, which will keep them from warping. However, you’ll need to add weight to the top of the stack so that the boards placed on the top don’t warp as well. 

You can also use narrow strips of wood between wood boards to increase ventilation and help them dry out faster. Once the wood moisture content reaches its EMC, you can transfer it to your storage area. 

Important Note: Make sure that you check and adjust humidity levels at least once every six months to keep your wood in good condition.

Final Words

Wood warping is a common yet unfortunate problem that can catch even the most experienced carpenters off guard. Understanding the reasons why it happens and using the right techniques are essential to prevent this problem from occurring.

We hope this guide will help you understand how to prevent wood warping so that you can work on your woodworking project without any hurdles. Once done, learn how to glue multiple boards together without warping.