Techniques to Prevent Degrade and Preserve Lumber Quality

Properly drying softwood and hardwood lumber can make the difference for buyers between a successful project and one that leads to costly moisture-related repairs.

When drying wood, it’s especially important to pay attention to lumber’s moisture content (MC) during the drying process to prevent degrade and maintain better lumber quality.

There are always going to be defects in some pieces of wood. But with proper drying techniques, those defects can be greatly reduced.

So to help you produce the best product possible, let’s talk about:

• Lumber degrade
• Differences between drying softwood and hardwood
• The best way to dry softwood
• The best way to dry hardwood
• How to prevent common drying defects
• How to handle and store lumber after it’s dried

Let’s start by taking a closer look at lumber degrade.

Understanding Lumber Degrade

Most degrade is caused by overdrying wood, which can lead to it shrinking and resulting in drying defects and lower value.

Drying wood too quickly can cause honeycombing, where wood fibers tear apart from each other.

If lumber is dried improperly, it can result in:

• Checking. Cracks can develop along the wood grain, leading to wood fibers being pulled apart
• Warping. Uneven MC distribution in wood can result in certain parts of wood shrinking more than others during the drying process
• Honeycombing. If lumber is dried too quickly, the outer layer of wood may be dry while the inner layers are still wet, causing wood fibers to tear apart from each other

These imperfections can significantly reduce the value and even the usability of wood.

The good news is, properly drying lumber can greatly reduce the chance of these wood defects and imperfections from developing.

Softwood Drying vs. Hardwood Drying

The cellular structure of softwood and hardwood are different, so they dry differently.

Most softwoods are lighter and more porous—meaning there are small spaces within the wood for air and moisture to pass through—so it dries more quickly. In addition, a lot of softwood is dried to just below 19 percent moisture content, which means it can dry to the final moisture much quicker than a lot of hardwood. However, softwood used for some furniture and other applications needs to be dried to lower MC levels, requiring more drying time.

Hardwood usually takes much longer to dry than softwood because drying hardwood quickly can cause a lot of defects. Additionally, most hardwood is dried to lower MC levels than softwood, so that can naturally prolong the drying process.

But whether you’re drying softwood or hardwood, the drying process for both needs to be carefully monitored to avoid wood defects.

Dry too quickly, and the wood might warp or split. Underdrying can lead to warping later on, or even possible mold growth—especially for softwood that has a higher final moisture content.

To get the best results for your lumber, follow these best practices for drying softwood and hardwood.

Best Practices for Drying Softwood

Use spacers within lumber stacks for even air flow.

Softwood is more porous than hardwood and is best kiln-dried by following these best practices.

• Stack the lumber in a covered, dry, ventilated area, so its surface isn’t affected by weather or sunlight but there’s still plenty of airflow. It should also be stacked on a higher foundation than the level ground so no moisture comes into contact with the bottom of the stack.
• Add a sealant to the ends of the boards to prevent the wood from drying too quickly and splitting.
• Use spacers, or stickers, evenly between each layer of wood so drying happens evenly within the lumber stack.
• Put a weight on top of the stack to prevent any warping during the drying process.
• Use a wood moisture meter to check the MC of several pieces of wood at the end of the drying process to make sure they’re actually dry.

Kiln-drying softwood normally provides good control over airflow, temperature, and humidity, but proper scheduling and temperature setting are vital.

• Using species-specific temperature, humidity, and airflow rates for the duration of the drying process can help avoid drying defects. Different wood species have unique drying schedules that work best for that kind of wood.
• It’s important to have the correct temperature and humidity at different intervals in the drying process. A person drying softwood usually starts with an industry accepted schedule for a particular dimension and species. Then after a person learns how the wood dries in their particular kilns, they can make adjustments to fine tune the schedules. The Forest Products Laboratory and some universities have recommended schedules for various species.

Best Practices For Drying Hardwood

Using a Wagner moisture meter with a stack probe accessory helps you protect the integrity of your lumber.

Because hardwood is more dense, it generally takes longer to dry than softwood. Drying must happen more gradually to prevent internal stresses and drying defects in the wood.

• Stack the lumber and place stickers between each layer of wood so drying happens evenly within the lumber stack.
• Add a sealant to the ends of the boards to prevent the wood from drying too quickly and splitting.
• Start with a lower temperature and higher humidity in the kiln, and gradually increase the temperature and lower the humidity so the MC throughout the lumber adjusts more evenly.
• Periodically check the MC of the wood using a moisture meter in different locations within the stack.

Using a moisture meter will help you verify that the wood is drying as planned, which then helps you prevent unintentional defects.

Common Drying Defects and How to Prevent Them

Excessive drying defects can occur because of improper drying techniques. Being familiar with the most common drying defects, including the ones below, is the first step in preventing them.

• Bowing. This is when the length of a board curves up, resembling the curve of an archery bow.
• Twisting. Opposing corners of a board can morph in different directions—one up, one down—creating a corkscrew shape.
• Case-hardening. When the outside of a board dries too quickly, it becomes rigid while the inside remains wet, because moisture gets trapped within the board. This creates tension in the wood.
• Cracking. When the outside of the wood dries more quickly than the inside, the internal stress within the wood causes it to crack.

To help prevent these drying defects, make sure there is even air circulation and weight distribution throughout the lumber stack during the drying process. These, and the following preventions, can help make sure excessive common wood defects don’t occur because of drying unevenly or too rapidly.

• Use the proper schedule for the type of wood and adjust temperatures and humidity gradually for a more controlled drying process.
• Since moisture escapes wood more quickly on the ends, apply a sealant coating to seal the ends of the lumber so moisture escapes in a more uniform manner. This will help prevent the wood from drying too quickly.
• Check the MC of the lumber in the stack with a reliable moisture meter, like a Wagner L5300 meter coupled with a stack probe.

How to handle and store lumber after drying

How you store wood is just as important as how you dry wood. Where lumber is stored can lead to imperfections in the surface of the wood because of its exposure to weather or direct sunlight.

Here are some tips to help prevent wood defects during storage.

• Use a covered space to avoid direct sunlight and rain.
• Store in a climate-controlled space, if possible.
• Continue to monitor the wood occasionally with a moisture meter.

Understanding the differences between hardwood, softwood, and the drying needs of the specific wood species you’re working with goes a long way. Using proper drying and storing techniques helps prevent defects in the lumber and preserves its durability, which in turn can help make your business more profitable.

And the right moisture meter can be the perfect tool to guide your decisions along the way.

Use Orion moisture meters so you can feel more confident in your drying process.

And check out Wagner’s selection of handheld industrial moisture meters with stack probes for the best tool suited for your lumber mill.

Wagner Meters

Wagner Meters is a family-owned American business that aims to provide solutions in moisture measurement technology that will enhance the quality and value of each customer’s project. With an almost 60-year legacy of innovation, Wagner continues to be a resource for both individual craftsmen and high-performance commercial endeavors.

Last updated on March 3rd, 2026