Sweet gum lumber is known for its beautiful grain patterns and rich reddish-brown heartwood color. However it also has a reputation for being tricky to dry properly without excessive warping and splitting. Here’s what to expect regarding dry times when working with sweet gum lumber.
Why Sweet Gum Dries Slowly
There are a few inherent properties of sweet gum wood that contribute to its slow difficult drying
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High shrinkage – Sweet gum wood shrinks around 15% from green to oven-dry, This is much higher than more stable species like oak or pine
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Interlocked grain – The fibers in sweet gum are twisted and interlocked, which restricts moisture movement and causes internal stress.
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Density – With a specific gravity of 0.50-0.60, sweet gum is considered moderately dense and heavy. Dense woods dry slower.
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Sapwood/heartwood difference – The different densities between sapwood and heartwood lead to uneven drying.
Air Drying Times
Air drying sweet gum lumber takes patience. Expect drying times of:
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1″ thick boards – Approximately 1 year
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2″ thick boards – About 2 years
The key is to sticker with maximum airflow on all sides. Shade the stack from direct sun. Expect significant warp (cupping, bowing, twisting) and end splits even with proper air drying.
Kiln Drying Times
Kiln drying reduces the total drying time substantially compared to air drying:
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1″ boards – 2-3 months
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2″ boards – 3-4 months
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4/4 lumber – 4-6 weeks
Use a kiln schedule that dries the wood slowly, around 3-5% MC reduction per day. The goal is to allow the wood fibers time to adapt and relieve stress gradually. Very fast drying risks too many defects.
Dehumidification Times
A dehumidification kiln with good airflow can dry 1″ sweet gum boards in approximately 4-6 weeks. Thicker lumber will take proportionally longer. The key is keeping air movement high and humidity low.
Partially Air Dry First
Many sawyers recommend air drying sweet gum lumber down to 15-20% MC before final kiln drying. This partial air drying relieves some internal stress before the final kiln phase. It can reduce defects like warp and splits compared to kiln drying only.
Post-Drying Conditioning
After kiln drying, allow the sweet gum boards to acclimate in the shop for 2-4 weeks before use. This conditioning relieves additional residual stress. Stickered stacks with spacers work best for maximum airflow around each board.
The Bottom Line
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Sweet gum requires slow, careful drying due to its high shrinkage and density.
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Expect 12-18 months to fully air dry material over 1″ thick.
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Kiln drying reduces total time to 2-6 months depending on thickness.
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Some air drying before kilning can improve quality.
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Proper conditioning after kiln drying is also advised.
With extra care, the beautiful color and grain of sweet gum lumber can be retained while minimizing defects. The extra effort is worthwhile for woodworkers who appreciate this unique species.
Is Sweet Gum any good for firewood?
FAQ
Is sweet gum wood worth anything?
How long does split gum take to dry?
Is sweetgum good for firewood?
How long do sweet gum trees drop their balls?
How long does sweet gum wood take to dry?
Individuals that are looking to use sweet gum wood for furniture or other wood decorations should consider steaming the wood prior to drying. This will help keep the RH stable and achieve an overall more vivid color. The wood usually takes about a full year to cure completely.
Does sweet gum move after drying?
In addition to this, the gum moves considerably after drying when the RH changes. Individuals that are looking to use sweet gum wood for furniture or other wood decorations should consider steaming the wood prior to drying. This will help keep the RH stable and achieve an overall more vivid color.
Can sweet gum wood be dried?
Drying sweet gum wood can be extremely tricky. This is especially true if you are going to be using the species for furniture. If you are simply going to be burning the wood then things get a little easier. The problem with sweet gum wood is that it tends to warp when it dries, as you learned above.
Does sweet gum wood shrink?
Some individuals will even use 12-inch sticker spacing to speed up the drying time. However, you will discover that through the seasoning process the wood will probably shrink right around 15%, which is much higher when compared to other firewood. It is the interlocking grain that makes the warping and splitting so prone with sweet gum wood.
Is gum wood hard to dry?
Bottom line is that it is a tough wood to dry. It is an underappreciated resource mostly due to these issues. My limited experience is that it is reasonably stable once dried. The excessive warp with gum is why it is not a commonly used wood. You can try 12″ sticker spacing and also very fast drying.
How hard is it to split sweet gum wood?
You can ask most experts and they will tell you that splitting sweet gum is probably more difficult than splitting oak. This is because when sweet gum wood dries out it tends to warp really bad. When it warps it get the fibers are interwoven and makes them even harder to cut through.