It’s no secret that vacuum kilns are becoming increasingly popular among woodworkers and furniture manufacturers. It is also standard equipment for modern wood drying use. Not only do they provide superior drying results, but they are also safer and more efficient than conventional kilns.
But how long does it take to dry wet wood in a vacuum drying kiln? And what are the best fast drying practices to achieve the best quality? This is a question that many people have.
When you dry lumber in a vacuum kiln, the wood drying length of time it takes will depend on the thickness of the lumber, the type of lumber, and the moisture level.
In this blog post, we will look at how long it takes to dry wet wood in a vacuum kiln, the factors that affect the drying time, and we will also provide some tips to speed up the process. Thank you for reading!
The Significance Of Drying Wood
Vacuum kiln drying uses a vacuum pump to suck out the air, and the wood drying process is carried out under vacuum conditions. After heating, the moisture evaporates. This allows for more precise control of the drying environment.
This drying type is often used for high-value woods, such as those used in furniture manufacturing, because it helps prevent damage and better color retention.
Vacuum kilns also allow for faster drying times, which is essential when time is of the essence. In addition, vacuum kilns can achieve deficient MC levels, making them ideal for working with woods prone to warping and denting. Therefore, vacuum kiln drying is an essential tool for anyone working with wood.
Vacuum Kiln Wood Dryer Time
Drying wood in a vacuum kiln usually takes as little as 24 to 48 hours.
The time needed depends on the thickness of the wood and the desired MC level. For example, thinner boards will dry faster than thicker boards. The MC of green wood itself is high, and the drying time is longer than that of timber stored for a long time
Also, if you are trying to achieve a very low MC, it will take longer than if you are aiming for a more moderate level. However, vacuum kilns are very efficient, so the drying process will be much faster than other methods, regardless of the specifics.
This is one of the many reasons why vacuum kilns are becoming increasingly popular in woodworking. Once the wood is dried in a vacuum kiln, it can be used for various applications such as construction, furniture making, and sculpture.
What Are The Factors That Affect The Drying Time Of Lumber?
Drying Method
Lumber drying is the process of reducing the MC of lumber. The lumber is dried so that it can be used for a variety of applications such as fuel, construction, and paper. There are three main methods of drying lumber: air drying, kiln drying, and solar drying.
Air drying is the most common method of lumber dries. It involves stacking the lumber in a well-ventilated area where it is exposed to the air. This is the slowest, easiest, and most economical way. It can take months for the lumber to dry, so it is important to plan ahead if you use this method.
Kiln drying is a much faster method of drying wood. Load the wood in the kiln and use controllable heating and humidity to remove moisture. This method is typically used for hardwoods that need to be dried quickly to prevent cracks and warps.
Solar drying is a low-cost method of drying wood that can be done without using any energy other than sunlight. The wood is placed in direct sunlight until it reaches the desired MC level. Solar kilns work by using the sun’s heating to remove moisture from the wood. Solar kilns take one to four weeks to dry wood, depending on weather conditions.
Wood can also be dried using a combination of these methods. For example, air-dried wood can be load in kiln-dried to achieve the following.
Types Of Wood
Wood can be divided into hardwoods and softwoods according to their processing characteristics.
1、Hardwoods
Hardwoods are mainly taken from broadleaf trees and are characterized by hard and heavy materials, high strength, natural and beautiful grain, solid texture, and durability. The common hardwoods are rosewood, walnut, ash, Quercus, red oak, camphor, boxwood, etc.
Hardwoods are generally more difficult to dry and are usually denser and harder than other types of wood. Hardwoods are often used for furniture and flooring because of their durability and strength.
They are also more troublesome to work with because they tend to crack and warp when exposed to moisture. For this reason, many woodworkers choose to vacuum kiln dry hardwoods before starting a project.
Hardwood is a wood that is known for its durability and strength. To ensure that hardwood lumber is properly dried and ready for use, it must be kiln-dried.
The vacuum also helps prevent the hardwood from bending or drying too quickly, which can lead to cracking or splitting. The entire process of vacuum kiln-dryer hardwoods takes approximately 3-5 days, depending on the thickness of the wood. Once properly dried, hardwood can be used for various applications such as flooring, furniture, cabinets, etc.
Therefore, vacuum kiln-dried hardwood is usually a worthwhile investment for those who want to create long-term projects.
2、Softwoods
Softwood is taken from coniferous trees, and this wood is characterized by smooth grain, uniform material, softwood, high resistance to corrosion, low density, and expansion and contraction deformation. And the common softwoods are red pine, white pine, fir, spruce, willow pine, horsetail pine, etc.
Softwood is also light and durable, making it an ideal material for many different products. The process of vacuum kiln drying softwood helps maintain these properties while also reducing the weight of the cork.
Vacuum kiln drying removes water from the cork cells, thereby reducing the overall weight of the cork without affecting its other properties. This process also helps to reduce the risk of mold growth, making kiln-dried vacuum cork an ideal material for a wide range of applications.
However, softwood is also very absorbent and must be properly dried before use.
Softwood can be air-dried for months, but this slow process can lead to bending and mold growth.
A vacuum kiln dryer is a more efficient method of dryer cork. A vacuum kiln-dryer usually takes two to three days, and it produces better results compared to air dryer. Therefore, vacuum kiln drying is the preferred method for preparing softwood.
Thickness Of Wood
Wood is a versatile material that can be used for various purposes. Depending on the finished product being made, the thickness of the wood varies; for example, solid wood flooring is usually 3/4″ thick, while engineered wood flooring is usually 3/8″ to 1/2″ thick, and a bookshelf may be only 12″ deep, but a dresser maybe 20″ deep.
Thicker pieces tend to be more expensive, but they also tend to be more durable. When choosing wood for a project, it’s important to consider not only the thickness, but also the type of wood and whether it’s been kiln-dried (which can make it less likely to warp or crack).
For example, softwoods such as pine are typically only 0.5 inches thick, while hardwoods such as oak can be up to 2 inches thick. When selecting wood for a project, it is important to consider the strength and stability of the finished product.
Thicker planks will be stronger and more resistant to warping, while thinner planks will be easier to work with and better suited for detailed projects. Ultimately, the best choice for any given project will depend on the specific requirements of the job.
The Pre-Existing MC Of The Wood
It‘s’ an important factor that affects the dryer process.
The average MC of freshly cut wood is between 50-60%. This means that for every 100 kg of freshly cut wood, 50-60 kg is water. Wood with higher water content takes longer to dry than wood with lower water content. Of course, different wood species have other moisture contents when they are freshly cut.
Finished solid wood furniture, flooring, cabinets, etc., require MC usually controlled at 8%-12%, and outdoor preserved wood before installation its MC control at about 13%-20% works best.
Drying Case Study
1. Country: Tanzania, Uganda Africa
Mahogany: Thickness 50-70mm, the Initial MC between 40%-50%; Target MC 8%-10%, The dryer time is 5 days
2. Location: UK
Black walnut: Thickness 75-100mm, the Initial MC between 40%-50%; Target MC 6%-8%, the dryer time is 8 days
3. Location: New York, USA
Eastern cottonwood: thickness 70mm, Initial Moisture:75%; Final Moisture:8%, the dryer time is 4 days
4. Location: Indonesia
Ash: Thickness 100mm, the Initial MC between 30-40%; Target MC 8%, the dryer time is 4 days
When you have read this article, you will have a more detailed understanding of the importance of drying wood and the approximate drying time.
I hope this blog can help you in your business.
If you have any questions you would like to discuss with me, feel free to contact me, and we can provide the best services!
