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Everything You Need to Know About Kiln-Dried Wood in a Nutshell

Everything You Need to Know About Kiln-Dried Wood in a Nutshell

September 19, 2022

What Is Kiln-Dried Wood and What is the Process?

For many people, purchasing wood furniture is the best way to add value and beauty to their home. Yet, not all tree to table woodworkers or salvaged wood sources create the same way, starting with the drying process. That’s why we work with a specific process. 

Our process involves a careful selection process of trees that would otherwise end up in a landfill, chosen for their unique beauty and features. 

We mill and dry logs to create the very best outcome. When you buy from us, you can expect exceptional results. 

Everything You Need to Know About Kiln-Dried Wood in a Nutshell

Where our wood comes from is important to us and our customers. We mill and dry our own wood for each wood product we sell. There are very specific steps for kiln drying that include sealing, stacking, and air-drying until the wood reaches a specific moisture point. Only at that point is the wood ready for the kiln.

As you learn more about our process, know that there are other providers who think air-drying is superior. We believe it is just one step in the process. We also see kiln drying as a necessary part of sterilizing the wood before it is used, as well as speeding up the process. That's why we put so much into this process. And, to be clear, our process is longer, and our tree concierge process takes more time. Here’s what you need to know about kiln dried wood to help you understand this process a bit better.

What Is Kiln-Dried Lumber?

Kiln-dried wood is just what its name sounds like. A kiln is a specific type of oven that's been used for thousands of years. You may know it from its continued use with pottery. This method of drying out wood is faster than air drying, but there are many other components to the process that make it one of the most important steps in creating wood furniture. 

Because wood absorbs moisture, there is a need to remove some of that moisture to help prevent the wood from breaking down. When placed in the wood, the green wood (which is wood that has not dried out yet) dries out, becoming more durable. This process is efficient and creates a highly durable and beautiful piece of lumber to use.

Kiln-Dried Versus Air-Dried Lumber

Many people talk about air drying lumber. However, there is a difference between this and the use of a kiln. Air dried lumber is a longer process that simply allows the air to dry out the wood. It may be beneficial for fencing and decking, but kiln dried wood is ideal for cabinetry, that live edge table you desire, and much more. This type of wood is less likely to cup or warp. It still allows the wood to retain its beautiful appearance. 

Goals of Kiln-Drying

The goal of kiln drying any product is to remove the moisture from it. If you imagine a piece of pottery that starts as clay, you can understand how the moisture within it makes the clay more flexible and soft. The same applies to wood. By placing it into the kiln, we can slowly and properly remove more of the moisture from it, which then allows the wood to become far more durable and stronger.

Moving the moisture to the surface of the lumber and then letting it into the atmosphere enables this to happen. It's done with controlled airflow as well as just the right amount of humidity and temperature. This allows the green timber to become more workable while also removing moisture that can lead to damage to the wood over the long term.

Benefits of Kiln-Dried Wood

Kiln-dried wood is carefully dried out over a period of time. During that process, the moisture is pulled from the wood. It helps reduce the risk of fungal degradation that is common in wood. When dried at the ideal temperature, softwoods harden because the temperature reduces the resin that is in the wood. 

When dried like this, the pieces become lighter in weight with less humidity. They become more durable while maintaining their overall beauty. In short, we believe this is a key part of the process of creating beautiful wood furniture.

Understanding the Kiln Drying Process

Take a look at the breakdown of what happens during our process.

Wood & Moisture

Trees are full of water. Because wood has moisture in it, we need to bring it down. The amount of moisture in green wood depends on many factors, but our goal is to get it down significantly.

Air Drying 

The drying process begins in a closed chamber where the airflow, humidity level, and temperature can be maintained to bring down the moisture level. Once we receive the wood, we place it in a stack called a boule. It remains there for six months for the start of the drying process. Once 70% of the water has evaporated from the wood, we move it on. 

Moisture Content

Once the water in the wood has dropped, we will then place the stack in a kiln. Over a very slow process that takes weeks, it will dry out until it reaches the desired moisture content level.

Shrinkage and Swelling

During this timeframe, the wood will change. There will be shrinkage and swelling. When the wood reaches 15% moisture content, it has reached about half the possible shrinkage and about 4/5 of the possible swelling. 

Methods for Drying Timber

There are a few different methods used for drying out timber. If you are planning to buy a solid wood table, you’ll want to know which method was used.

Kiln Drying 

Most of the time, kiln drying is done with conventional and dehumidification kilns. The process involves drying out wood that is placed within a chamber. There, the air circulation and relative humidity, and temperature levels help to reduce the amount of moisture within the wood. This can be done until the desired moisture content is reached. There are several styles of kilns to know.

Dehumidification Kilns

These are the most commonly used option for wood products because they have continuous recycling of heat in the kiln. It does not discharge that heat from outside of the kiln as conventional kilns do. 

Vacuum Kiln 

In this type of kiln, there is limited drying capacity within the chamber. This method provides a very high-drying speed, which is why it is sometimes used, but it limited in its success for thick slabs and some other cuts.

Solar Kilns

Most kilns use electricity, but some use solar power. That’s an added benefit to the planet, but it doesn’t get hot enough to sterilize the wood.

Types of Wood

The types of woods used in this process will vary significantly. It also influences the overall outcome. Here is a look at some of the types of woods commonly used in this process.

Hardwood 

Hardwoods can be placed in kilns without a problem. That includes oak, ash, maple, polar, and birch, among others.

Softwood

Softwoods are often from trees that have needles rather than leaves. These woods are much softer overall. They will fire faster and dry out quicker. Pines are a common example of softwoods.

Schedules: From Felling the Tree to Delivering the Furniture

Once the tree is felled, the next step is to bring it to our location. There, we will seal the ends of logs and mill it into slabs or quarter sawn lumber. The wood sits in our location for at least six months as it drops to a lower moisture level. Once that happens, it will spend several weeks in a kiln as it dries out and reaches its desired goal.

It takes time for the wood to reach the desired level, and there is no rushing that process. Once it reaches the correct moisture level, we then need to plane it into the proper dimensions. It is then graded for use. 

Acclimation After Kiln Drying

Once the wood reaches the desired level of moisture, it is then placed in our barn to reacclimatize. This is done to allow the wood to absorb the moisture in the area. That takes some time. If you were to put hardwood floors into your home, this process is necessary. It needs to sit in place to reach the humidity level within that space. This helps to minimize the risk of damage to the wood once it is being worked.

How We Do It At Alabama Sawyer

We seal the ends of logs when we receive them as our first step. We then stack and sticker them for airflow. Our goal is to air dry hardwoods until they reach 30% moisture. We then use a dehumidification kiln to bring the wood to below 10% moisture. Because Alabama is so humid, that might go back up to 12% when it lives in our covered wood barn.

Our careful and slow process helps distinguish us from similar businesses that may not use kiln drying or air drying. When you purchase wood furniture or kiln dried slabs, you need this high-quality process that takes time and gets superior results. 

Take the time to learn more about our process. If you are looking for the very best in wood products, you want Alabama Sawyer.