Are you looking for Kiln Dried Vs. Air-Dried Lumber for furniture, which is better? Kindly go through this article to find out
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I was a freelance carpenter and took orders to build personalized furniture from the neighborhood local furniture stores. The store used to provide me with lumber, and I just worked on it. After many years, I was able to open my furniture store.
I thought I would buy green lumber from a mill and let it air dry for a year or so for the wood supplies. Eventually, its moisture content will come down to my area’s moisture content, 12-14%. I was confused about what type of wood I should use for my furniture and went to the neighboring stores for consultation. The reviews were 50-50, and I got even more confused. Some say you should always use kiln-dried lumber for furniture.
So I took to the internet to find answers, and I found out that air-dried or kiln-dried both have their pros and cons. I wrote this review to help others with the struggle of what kind of wood is better? My review is based on moisture content, sturdiness, cost, the time taken to dry, reaction to season change, and bugs.
Kiln-dried vs. air-dried for furniture, which wood is better? Let’s find out, shall we?
Why Does Wood Need To Be Dried At All?
Before I go on to explaining the virtues of kiln-dried and air-dried, the more astute in my readership would probably be asking: why dry wood at all?
The reason is that natural wood has a very high moisture content (It can go from 30% to above 100%). However, wood loses moisture steadily when exposed to any environment until it reaches the same moisture content as its surrounding atmosphere. Ideally, for lumber used in furniture, this means the wood will reach the range of 6-12% moisture content, depending on where you live.
Now, if you make furniture directly from greenwood without drying it first, the wood will start shrinking (due to loss of water). It may become crooked, and your furniture will end up looking completely out of shape in a few months. That’s why we always use dried wood to make furniture. To understand this better, you can watch the below informative video:
Kiln Dried Lumber
Kiln-dried lumber is wood dried in an oven for quick use. The oven used to dry it is called a kiln. You can control the environment, such as temperature, humidity, and steam levels, for a set time. The kiln also kills larvae and insects if you turn the heat up to 150 degrees in the last few days of drying.
Kiln drying is proven to be effective for removing molds and insect infestations from logs and timbers. A kiln is a fast and forced process of drying the wood. The temperature is raised slowly to 170 degrees Fahrenheit to dehumidify the wood and remove moisture gradually. After the wood is removed from the kiln, the moisture content (MC) that remains is usually in the range of 6-10%.
The process is not as easy as it sounds. The wood has to be monitored to check that it is not cracking. Cracks occur due to uneven drying of the wood. The temperature is checked from time to time; otherwise, it dries the surface and leaves the core moist.
It would feel the same working with an air-dried one but with lesser moisture content. Kiln-dried woods can be used for making furniture, cabinets, and flooring.
Pros
- Much quicker than air-drying.
- Lesser moisture content
- Weights 20-30% less than air-dried lumber
- Removes larvae, pests, mold all in the same process.
Cons
- More expensive than air-dried lumber
- Exposure to steam in the kiln discolors the wood.
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Air-Dried Lumber
Air-dried lumber is dried in an open area, completely in nature, and without any artificial heat applied. After trees are harvested, logs are sent to the sawmill for cutting them into boards. Once the boards are ready, they are attacked with spacers and kept in the natural sunlight and air. The spacers keep the boards separate and ensure each board gets equal air.
Natural sunlight and air take away most moisture and leave the wood with just 30% moisture content and 70% wood. This process can take anywhere from 1 year to 2 years. The time also depends on the thickness and species of the wood. The moisture content left in the end will depend on your environment, i.e., it follows the equilibrium rule. It will lose its moisture until no further moisture can be lost or gained.
There are so many factors to consider while air drying the wood like you, will have to protect them from rain and sometimes even from theft. When so much wood is lying around for so long, some evil intended might get lured.
Some manufacturers even air dry the lumber for 8-9 months for partial drying and keep them in the kiln for complete drying. Air dry allows the woods to naturally shrink and take shape before they can be used for furniture. This air-dry process can also be done before sending the logs into the sawmill to know the shrinking and cut the boards accordingly. Air-dried lumbers used in making patio furniture, fencing, and decking.
Pros
- The natural dried color is maintained.
- Way affordable and easy process of drying
- Since it is naturally dried, there is no internal tension in the woods.
- Even in climate change, the air-dried woods do not absorb moisture that easily.
Cons
- It is a slow process and takes a lot of time.
- Insects and larvae do not get killed; they might even serve as a home to more.
You might also like to read: Alternatives To Pledge For Wood Furniture
Kiln Dried Vs. Air-Dried Lumber for furniture: Features and Benefits
Moisture content
Air-dried lumber often follows the equilibrium rule with the environment that it will lose its moisture until it is equal to natural moisture content. It cannot lose moisture anymore or gain any moisture. And hence, the humidity in the area where you are planning to air dry the woods would decide the moisture content, but it does lose 70% of the moisture.
You can decide Kiln-dried woods’ moisture content. The temperature and steam of the kiln generally leave the woods with only 6-10% moisture content if performed evenly and adequately.
Winner: Kiln Dried lumber. You can control the MC perfectly.
Expense
The price of the wood is decided by taking into account all the equipment required for the drying process. We require spacers, a canopy/plywood to protect them from water. Natural sunlight and air and an open area with no big trees ensure the floor is not wet.
Sometimes, the unavailability of air-dried lumber might increase the price if the demand is high. This would probably happen if few lumber traders can only restock after the next batch is ready to be used and sold. But it will always be cheaper as compared to kiln-dried lumber.
The whole oven is equipped with so many machines to maintain temperature, streamflow, huge fans, and insulation for wood dried in the kiln. It is a huge oven for woods. And hence the expense to keep your woods in the kiln is high.
Winner: Air-dried lumber. It does not need any special equipment, so it’s pretty cost-effective.
Appearance
Air-dried lumber is good at keeping its beautiful wood color since it is allowed to age naturally. The cracks and lines created naturally give the furniture its woody look.
While kiln-dried woods tend to lose their color from the bleaching effects of the steam blown on them to dry them fast, you have to face some consequences if you are speeding up a natural process.
Winner: Air-dried lumber. The natural look is unbeatable.
Weight
Kiln-dried woods lose up to 60-70% weight while drying compared to green(fresh) lumber. The shrinking of soft ligaments in the woods under extreme temperatures takes out most of the moisture(which contributes towards the weight).
While air-dried lumber being natural only loses a maximum of 50% weight of the green lumber. The moisture content will also contribute towards the weight as the green lumber is the heaviest as it also carries water’s weight.
Winner: Kiln-dried lumber is less heavy.
Ease of use
Air-dried lumber is easier to work with, especially if you are a hand tool worker. Due to the natural process, the cells of the wood collapse and get stuck together due to compression.
With kiln-dried lumber, as it is forced to lose moisture, the cells do not act the same way and then create a brittle texture, which is hard to work with. It ensures that it does not get twisted or warped once fitted in interior furniture but will make your tools blunt easily.
Winner: Air-dried lumber is a lot easier to work with.
Reaction to climate change
Kiln-dried lumber, when exposed to varying moisture or humidity, will absorb or lose moisture. This would either lead to shrinking or swelling of the furniture. This happens because the cells are not at equilibrium with the environment.
Air-dried lumber is naturally brought to equilibrium moisture content with the environment. Once the cells get adapted according to the moisture content, they will not swell or shrink with climate change. The woods had already adjusted to the climate when it was kept out for drying.
Winner: Air-dried lumber. The natural process is always the best.
Interior and exterior use
Air-dried lumber is versatile due to the exposed climatic conditions, while drying becomes immune to the humidity change. This quality makes it perfect for external and internal use. Now it’s explained why we often use air-dried lumber in fences.
Kiln-dried lumber fails to keep its shape and moisture when there is humidity change. This happens because the cells are forcefully parched of moisture and hence do not settle well. The slightest availability of moisture will lead them to absorb it and swell. We can say kilns are better for internal use.
Winner: Air-dried lumber is better resistant to weather.
Pests control
Air-dried lumber is not good at keeping pests and insects at bay. You will have to use pesticides or an anti-bug oil on the lumber before making furniture. Bugs and pests survive in nature, and hence they might find a home in the woods. Some bugs leave once there is no moisture, but since the content is equal to the surroundings, all the bugs that can survive in the surrounding areas will survive in the woods.
Kiln-dried lumber easily eliminates all the insects, molds, and bugs as no pest can survive at such high temperatures. This is why nowadays, traders first air-dry the woods to get rid of most of the moisture and then drop them in the kiln for pest control and even less moisture content.
Winner: Kiln-dried lumber is free of insects, bugs, and mites.
Cracks
Air-dried lumber and kiln-dried lumber both develop cracks while drying. It’s a natural phenomenon to develop cracks as the wood loses moisture and the ligaments are shrinking.
The difference between the cracks in air-dried and kiln-dried is that the air-dried ones look natural. In comparison, kiln-dried ones might indicate that the wood is roasted from outside and still wet from the core, which is defective wood.
Winner: Air-dried lumber does not crack.
Final words
In this article, we deeply examined kiln-dried vs. air-dried lumber for furniture. We saw why kiln-dried lumber’s high price is justified, why it is better to use the air-dried lumber for external use or furniture in the proximity of moisture.
Use the kiln-dried lumber if:
- You want to use mostly internal furniture.
- You don’t want the smell of pesticides.
- We are looking for lighter lumber.
Use air-dried lumber if:
- You want strong and weather-resistant wood.
- You don’t want to compromise the original color of the wood.
- You want wood for external furniture.
