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?
- 4 The Importance of Moisture Content in Wood
- 4.1 • Accelerated Drying Using Commercial Dehumidifiers
- 4.2 • Special Microwaves: A Technique With Caution
- 4.3 • My Step-by-Step Guide to Drying Lumber Correctly
- 4.4 • Ideal Moisture Content for Woodworking Projects
- 4.5 • Time Requirement for Each Drying Method
- 4.6 • Cost Implications of Drying Methods
- 4.7 • Selecting Wood Types for Each Drying Method
- 4.8 • Proper Stacking for Air Drying
- 4.9 • Safety Precautions for Microwave Drying
- 4.10 • Using a Moisture Meter Correctly
- 4.11 • Factors Affecting the Drying Process
- 4.12 • Consequences of Improperly Dried Wood
- 4.13 • Alternative Methods for Drying Wood
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.
The Importance of Moisture Content in Wood
Having the right moisture content for your wood before usage is essential. The most recommended percentage of moisture in wood is below 7%. Such a level ensures the wood is in perfect condition for use.
The presence of high moisture content is the number one catalyst for wood warping, cracking, and being unsuitable for crafting structures. It can translate into substantial losses, especially in construction and carpentry projects. Proper handling of wood is essential in preventing such occurrences.
• Accelerated Drying Using Commercial Dehumidifiers
When you’re faced with a bulk of wood requiring quick drying, commercial dehumidifiers are the gadget to turn to. Thanks to their efficacy, these machines can be rented to hasten the drying process of the wood significantly.
They work by reducing the moisture content in the circulating air inside the kiln (or wherever the lumber is kept), which in turn reduces the moisture content in the wood. It’s an easy, efficient method that doesn’t require too much effort, especially when large volumes of wood are concerned.
The University of Tennessee Agriculture Extension provides more information on how exactly these devices work and when to use them.
• Special Microwaves: A Technique With Caution
An unconventional yet efficient solution for drying wood is using special microwaves. These are not your average kitchen microwaves.
They are designed specifically for the purpose of drying wood. They heat the wood uniformly and quickly reduce the moisture content. However, they do come with a bit of caution. There’s a risk of scorching the wood if the temperature gets too high or if the wood is left in too long.
It’s advisable to use a microwave for smaller wood pieces rather than large planks. Always remember the golden rule: moderation is key. Be sure to keep a keen eye on the process to prevent overheating, which can cause irreversible damage.
• My Step-by-Step Guide to Drying Lumber Correctly
The process of correctly drying lumber is not a simple one, coming with a few notable specifics that need adherence. Here is my recommended step-by-step guide that will ensure you get it right:
- Checking the Moisture Level: Always ascertain the moisture level of your lumber before and after drying. The aim is to ensure it is below the recommended 7% for optimal use.
- Stacking Correctly: Proper stacking of wood ensures even exposure to air and heat for drying. Use “stickers” to separate wood layers and ensure even weight distribution.
- Preventing Warping and Cracking: These are the most common issues with drying wood. To prevent warping, use weights on top of your stacked lumber to apply downward pressure. To prevent cracking, avoid drying your wood too fast. Gradual moisture loss is the key.
- Keeping an Eye on the Temperature: Keep your drying temperature moderate. Too much heat can cause the wood to lose too much moisture too quickly, resulting in cracking and warping.
These are not exhaustive instructions; a more detailed guide can be found on the University of Minnesota Extension’s website.
By observing these steps and precautions, you’ll achieve the optimal moisture content of your wood, much below 7%, ensuring your wood is of the best quality for whatever purpose you intend. Remember, the key to drying wood correctly is patience and vigilance.
• Ideal Moisture Content for Woodworking Projects
Determining the ideal moisture content for wood used in woodworking projects is crucial. The acceptable range for most wood types lies between 6-8% moisture content.
Having uneven or excess moisture can lead to various issues such as warping, cupping, and even decay. The University of Maine has provided an educational resource which explains this in detail.
• Time Requirement for Each Drying Method
Numerous factors, such as wood species, thickness, initial moisture content, and relative humidity, can influence the drying time. Air drying, the simplest and most cost-effective method, can take several months to a year.
Kiln drying, on the other hand, can drastically reduce this to a few days. However, it requires significant energy input and specialized equipment.
• Cost Implications of Drying Methods
Air drying is a cost-effective method as it uses natural resources. However, it demands a lot of time and space.
Kiln drying is faster but involves substantial costs due to energy use and initial set-up expenses. Both methods have their pros and cons; choosing the right one depends on the urgency, volume, and scale of the project.
• Selecting Wood Types for Each Drying Method
Different wood species respond distinctively to the drying process. Hardwoods like oak and maple are more prone to cracking and take longer to air dry but can be kiln-dried effectively.
Softwoods like pine and cedar air dry relatively faster and with less risk of cracking. It’s essential to choose the right drying method for the right type of wood.
• Proper Stacking for Air Drying
Stacking wood properly optimizes air circulation and minimizes warping or molding. Boards should be stacked with weights evenly distributed on them. Stickers should be inserted between each layer for air circulation. The pile should be restacked halfway through the drying process for more uniform drying.
• Safety Precautions for Microwave Drying
Microwave drying is another method to dry small wood pieces. It’s vital to monitor the process since overheating can cause a fire risk. One should use microwave-safe containers, avoid using metal, and select the defrost mode to prevent rapid heat build-up.
• Using a Moisture Meter Correctly
A moisture meter is an essential tool used to measure the moisture content of wood. Always calibrate your meter according to manufacturer instructions.
Insert the pins or sensors into the wood, avoid the end grain, and always take multiple readings. The average of these readings provides a fairly accurate moisture content.
• Factors Affecting the Drying Process
Environmental conditions like temperature, humidity, and air circulation significantly influence the wood drying process. A drier environment results in quicker drying. Initial moisture content is also crucial; high initial moisture requires more energy and time to dry.
• Consequences of Improperly Dried Wood
Woodwork created from improperly dried wood may have compromised strength and durability. It can lead to warping, bulging, shrinking, and cracking, ruining the integrity and aesthetics of the finished product. In extreme cases, fungal growth and decay might occur, leading to structural failure.
• Alternative Methods for Drying Wood
Apart from air drying and kiln drying, there are a few alternative methods like solar drying, using a drying closet, and chemical drying. Especially worth considering is kiln drying services where a third party handles the drying process, benefiting those who lack the equipment or space.
Let’s practice the best woodworking techniques to ensure we produce only the best woodwork pieces. Keeping these points in mind, one can confidently navigate the process of drying wood for their woodworking projects.
Remember, patience is key in the drying process, as rushing it may result in a substandard final product.