Drying lumber is an important process that is required for wood, especially those used by woodworkers. Although it is technically possible to build or work with green (fresh) lumber, it is not recommended because wood tends to absorb moisture rapidly and lose it slowly. Once you attempt to assemble or build woodworking projects with wet or green lumber, there are some results you’re expected to get.
These include warping of the materials and cracked or split joints. If you’ve taken some time to get lumber by yourself or you even purchased green lumber for your project, then you should consider drying it, as this is an essential factor for your woodworking project.
How to Dry Wood Fast for Woodworking:
Generally, there are 3 main drying methods: Air Drying, Shed Drying, and Kiln Drying. Air drying is slow, Kiln drying is much faster. Air drying and Shed drying depend on the environmental climate. Kiln drying is more expensive but has a uniform result. What method to choose depends on the type and amount of the wood.
Regardless of the kind of woodwork project you’re using the fresh lumber you obtained to do, adequately drying the wood is undoubtedly required. You’ll want to dry your lumber effectively as you’ll be dealing with a certain degree of shrinkage once the wood eventually dries.
There are several options to consider when deciding on the best method or way to dry wood, and they all depend on the size and thickness of your lumber. While some drying methods may limit you as regards the thickness of the logs you’ve cut, there are still some feasible alternatives that do not consider factors like the thickness, size, or type of the lumber.
In this article, I will guide you through the different methods of wood drying as well as the pros and cons.
- 1 Different Wood Drying Methods
- 2 What Kiln Drying method to choose
- 3 Do You Have to Dry Wood Before Using It?
Different Wood Drying Methods
Several methods can be used to dry lumber. From air drying to kiln drying and special seasoning processes, all methods involve the removal of moisture from within the wood to the surface, where it is then evaporated into the air. The major factors that make drying possible and faster are heat and air movement.
If you only have a limited amount of wood, you can also use a dehumidifier or a microwave. I will explain those methods at the end of this article.
Below are the three main methods of drying wood:
● Air Drying
This involves employing sunlight and natural wind to dry wood. Air drying is done by stacking lumber on stickers and allowing the wind and sunlight to pass through the pile for drying. However, this method has some disadvantages. Slow drying which results from low airflow or high humidity may result in stains. Fast-drying on the other hand, which is caused by excessive air flow can result in unsightly cracking and splitting.
If the lumber is required for furniture or other finished products that require 6% – 8% moisture content, then air drying will not achieve the result by itself. Although air-drying is simple and easy, it is quite common to have over 10% loss in quality which is a result of the variability and extremes of the weather.
– Pros Air drying
- Less expensive: This method is less expensive to use (in fact, it is more economical when you need to air dry timber to a moisture content of 18% – 25%.)
- High quality: The end products of air drying are usually woods of a higher quantity, quality, and those that are more workable than kiln drying.
- Vibrant colors: Lumbers gotten from air drying have more vibrant colors.
– Cons Air drying
- Takes a long time: Depending on the weather condition, air drying can take up to several months or even some years to completely air-dry the wood. In the cold winter months, the drying rate is extremely slow, especially in the northern part of the country.
- Degradation: In hot weather conditions, the hot, dry wind flowing through the wood may increase degradation and volume losses due to the severe surface checking and end splitting.
- Low moisture difficult: In air drying, moisture contents of less than 18% are usually difficult to attain for most locations.
● Shed Drying
This method involves placing lumber in a shed that has no walls, thereby preventing direct contact with sunlight and rainfall, while still allowing for good airflow. In this drying method, drying rates are often regulated by the use of plastic mesh curtains, opening them during damp weather conditions and pulling them closed during hot and dry weather conditions.
The construction of the sheds can be very simple, but they can also become complex by adding adjustable walls and by adding fans. These fans are powered by electricity (which may incur additional costs) and are used to remove excess moisture from the woods. This process may slow the drying rate at the beginning when some species are susceptible to checking.
– Pros Shed Drying
- Low moisture content: In this method, the final moisture content of lumber is typically over 20%.
- Depending on environmental conditions: Similar to the air-drying method, the final moisture content is determined by the ambient temperatures and relative humidity.
- High quantity: If you shed-dry before kiln drying, the annual volume of lumber dried in the kiln can be tripled or even quadrupled unlike when you kiln dry green lumber from the saw.
– Cons Shed Drying
- High investment: The cost of investment is fairly high in proportion to the amount of drying that will be accomplished.
● Kiln Drying
Kilns are closed chambers where air circulation, temperature, and relative humidity can be controlled so that the moisture content of the wood is lowered to a specific point where there are no drying defects. There are different types of kilns, some of which include vacuum systems, traditional heat and vent types, and radiofrequency dryers.
While kiln drying is effective, the cost of installing and maintaining the kilns may be the prohibitive reason, except if the throughput of the timber is high. If the value of certain species of green timber is high enough, it becomes more feasible to kiln-dry them. Kiln drying may be done directly by using natural gas or electricity, or indirectly, with steam-heated heat exchangers.
– Pros Kiln Drying
- Low moisture content: Lumber dried through kiln drying have lower moisture contents than air drying
- Not depending on external conditions: Kilns can be used in countries with cool or humid weather conditions for most indoor applications.
- Controlled result: Your lumber can be dried to any desired low-moisture content as the drying conditions can be relatively controlled
- Uniform moisture content: More uniformed moisture content is observed throughout the wood.
- Brighter lumber: Kilns are faster and produce brighter lumbers
- Fast: Drying time is relatively reduced (up to one-third) as well as the presence of drying defects.
– Cons Kiln Drying
- High initial investment: Kilns are usually quite expensive: high initial investment, as well as high energy costs. It is required that they are fully utilized, running 24 hours a day, 7 days a week.
- Loses color: Wood dried by this method often loses about 20% of its color, even when it is not steamed. This is due to the high temperature of the kiln.
- More fragile: Woods produced are more fragile and break or chip easily, especially when you’re working with hand tools or powered saws and knives.
What Kiln Drying method to choose
Typically, the factors that determine the drying process often depend on the size of the operation. For instance, a sawmill that produces a considerable volume of slow-drying wood will most likely select air drying, followed by kiln drying.
Softwoods on the other hand are often kiln-dried green from the sawmill. The major purpose of air-drying lumber is to remove as much water as possible while reducing the cost of dry-kiln capacity as well as the energy requirements. In air drying, lumber is often placed on stickers until the moisture content reaches 20% – 25%.
The lumber may then be ready for use or require further processing, depending on the end use. If lower moisture content levels are required, such as for use in furniture factories, then the lumber will be kiln-dried. When the end-use of the lumber does not require low moisture contents, air drying is usually sufficient.
Rough sawn hardwoods are usually air-dried at the producing sawmills to reduce the weight as well as the shipping costs. One of the major benefits of air-drying, particularly for hardwoods, is that it provides a way to add value. Air drying can also be used occasionally to reduce the moisture content in woods such as railroad ties, to a level where preservative treatment is suitable.
Kiln drying reduces the chance of mold growth and decay while the wood is being shipped, stored, or in subsequent use. Wood-degrading fungi and blue stain cannot grow in wood with 20% moisture content or less.
Although some green lumber may need to be treated with fungicide to protect it from fungi, especially in the early stages of the air-drying process.
Always remember that whatever you choose to do, ensure that the wood has a moisture content of less than 7% contained in it. Also, it is important to have a moisture meter to help determine the exact or correct moisture content.
Once your wood has attained this moisture level, then it is ready for work, and you can now produce excellent woodworks and crafts without worrying about any potential defects caused by unwanted water content in the wood.
Do You Have to Dry Wood Before Using It?
Generally, you should always dry your lumber before using it. Using wet or green lumber for your projects will often result in cracking or warping. Drying is an essential part of working with wood.
There are several methods to dry your lumber fast, as I have explained in this article. If you have only a limited amount of wood to dry, there are two other additional methods you can use:
● Limited amount of wood to dry: Dehumidifier
If you do not have to dry a lot of wood for your project, you can also use a closed room with a dehumidifier. You can use a residential dehumidifier, but I always recommend renting a commercial dehumidifier. They can remove a lot more water per hour than a residential dehumidifier.
A dehumidifier pulls in the moisture from the air and dries it out to release dry air back into the room. When used with a fan, this can be highly effective at drying out the drywall quickly.
● Limited amount of wood to dry: Microwave
Another method you can use if you only have small pieces of wood to dry is to use a microwave. This method is probably the fastest way of drying wood.
There are special microwaves for drying wood, but you can also use a regular microwave for it, as long as the wood fits. But always be extremely careful with this method. If you keep it in for too long, you can scorch the core, and destroy the wood.
I always recommend using a lower microwave setting, and only for a limited time. For a 1 to 2 inch thick piece, start with 2 to 3 minutes at 500 Watts. Remove it from the microwave and use a moisture meter to check the moisture content. Repeat this process until you reach your desired level.