When I started cutting lumber for myself, I thought I could do it better than Home Depot. No more twisted and crooked lumber for this guy. I planned to be the person who did it right, who wasn’t limited by the amount of work that could be done, who made sure that every step was taken and that every board behaved. I thought that the lumber would respond in kind if I put the sticks in the right places, used more sticks, weighed down the pile, and paid attention in other ways. Boy, was I wrong.
In my early days as a mill worker, I tried to dry some gum. It’s one of my favorite stories to tell. The customer asked me to cut the tree log into 4′′ wide boards so they could be used as flooring. I stuck that 4′′ wide piece of sweet gum on the bottom of a stack of lumber that was as tall as the Bobcat could reach. There must have been at least 3,000 bd. ft. and another a billion pounds of sweet gum to help keep the notoriously wacky wood flat while it dried.
After a few months on sticks, the lumber had twisted in unimaginable ways. Some of the boards twisted 45 degrees. They somehow pushed up the whole stack as they dried and went on their way, getting all crooked even though my stickers were in the right place and the extra weight didn’t bother them. It was really incredible. Even if I showed you a dried board in person, you may not have believed it. Some of the wood was only 8 inches long, so I had to cut it down to make it straight on the jointer before it went through the planer. I don’t cut sweetgum anymore.
After my sweetgum “education”, it was clear that some wood is just not going to dry straight. Certain species always dry wonky. Flatsawn sycamore, elm and cottonwood all come to mind, along with the sweetgum, as bad actors. If quartersawn, they are all more stable, but if flatsawn, all bets are off. I always say that flatsawn sycamore dries like a potato chip. Elm and cottonwood dry more like thinly sliced potatoes that are fried in oil.
And, it isn’t just certain species that twist. If you grow branches or trees with a lean, they will dry out crooked, even if they came from species that usually work together. Certain areas within the good lumber can dry crooked too. Wood that is close to a branch or crotch always dries spastic because the grain is going in lots of different directions. You can still get crooked lumber if you don’t cut it with the tree’s pith running down the middle of the board. There are just too many forces in the world trying to make the lumber unstraight.
The last one, and the one that I cannot defeat, is the tree with a twist. Not twisted lumber, but a twisted tree. The twist gets in the tree as it grows, and it twists the lumber as it dries. I have seen it in may different hardwood trees and the resulting lumber is always twisted. I took a picture of a dead sycamore this summer that showed this “death-twist,” which would make a wooden worker who is already very angry lose it. It is easily identified by looking at the surface checks in this dried out log.
Sycamore doesn’t always look like this. The grain is normally wavy, which makes the lumber dry unflat, but it isn’t usually twisted. This tree is very, very twisted and will dry with a pronounced twist in every board. It is best left as a decoration in the field. The good news is that this twist is usually obvious, even when the bark is on the tree. There will be twisted lines in the bark that match those in the log. This means that it is not worth milling.
But in the world of sawmilling, not many logs just stand there and say they’re going to twist. They don’t say, “Don’t waste your time cutting me, idiot!” Many logs and pieces of lumber look nice but do what they’re supposed to do, and you have to accept that some lumber will not dry flat. I still do everything I can to make sure the wood dries straight, but I know that crooked wood is just a part of life. Over the years, I’ve become very close with my jointer.
Sweet gum is a common hardwood species found throughout the eastern United States. It is known for its beautiful grain patterns and distinct reddish-brown heartwood. However sweet gum is notorious for being challenging to dry properly due to its tendency to warp and split. So how long does it actually take to dry sweet gum firewood?
The Challenges of Drying Sweet Gum
There are a few factors that make sweet gum more difficult to dry compared to other hardwoods
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High shrinkage rate – Sweet gum shrinks around 15% from green to oven-dry. This is much higher than many other woods.
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Interlocking grain – The fibers in sweet gum are arranged in an interlocked pattern which restricts moisture movement and exacerbates warping stresses.
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Tension – Sweet gum logs often contain significant internal tension which gets released as the wood dries, causing distortion.
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Low permeability – Sweet gum is less permeable than most hardwoods, slowing the rate of moisture loss.
These traits lead to major checking, splitting, bowing, cupping, and twisting as the wood dries. It’s not uncommon to see over 20% losses during drying.
General Drying Times
Most sources estimate sweet gum requires at least 6-12 months seasoning time to adequately dry firewood splits from fresh cut to useable moisture content. This can vary substantially depending on climate conditions. Colder northern areas may need 12+ months, while warmer southern climates can dry it in 6-9 months if stacked properly with good air flow.
Here are some general guidelines for drying times under different scenarios:
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Air drying splits in open stacks: 8-12 months
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Air drying rounds: 12-18+ months
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Kiln drying: 4-8 weeks
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Drying time after rain/snow: Add 2-4 weeks
Note that even after extended seasoning, sweet gum firewood is notorious for reabsorbing moisture quickly compared to other woods. Plan to burn it soon after drying.
Tips for Faster, More Effective Drying
Here are some tips to help accelerate drying and minimize defects when seasoning sweet gum firewood:
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Cut logs in early winter and let them sit for a few months to release internal stress before bucking and splitting.
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Use wedge-shaped splitter blades to help follow interlocked grain direction.
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Split immediately after felling before drying defects begin.
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Seal log ends with wax or end sealer after bucking.
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Stack off the ground with excellent airflow in a sunny location.
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Use narrow sticker spacing around 6-8 inches. Wider spacing causes more bowing.
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Apply weight on top of stacks to restrict warping.
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Rotate and restack splits every 2-3 months for even drying.
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Consider solar kiln drying or dehumidification kilns to accelerate drying time.
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Don’t leave seasoned wood exposed to rain or snow. Cover or bring inside to keep dry.
The Bottom Line
In most cases, sweet gum realistically requires about 8-12 months seasoning time to reach usable moisture content for burning. This can be shorter in drier climates or if using kilns, but air drying logs or rounds will take over a year in many areas. Proper stacking, sealing, and handling can help minimize drying defects and speed the process. But no matter what, sweet gum is a challenge compared to woods like oak, hickory, and ash. Be prepared for checking, splitting, and warping issues if tackling this species for firewood.
Is Sweet Gum any good for firewood?
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.
How can one stop gum shrinkage?
Gum shrinkage can be stopped by regular brushing of the teeth twice daily, avoiding vigorous brushing of the teeth, rinsing the mouth with antimicrobial or chlorhexidine mouthwash, avoiding smoking and chewing tobacco, using a soft-bristled toothbrush, flossing every day and getting regular teeth cleaning done by the dentist.
How long does sweet gum last?
Once the wood is split, store it under a roof or cover because sweet gum tends to rot quickly and produce mold when it’s exposed to moisture. Let the wood season for about 1 year and it will be ready to burn. Sweet gum works good for the “shoulder seasons” when the outside temperatures are mild.
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.