Drying live edge slabs properly is a process that can take over two years. I know, you just cut some beautiful slabs that you're ready to use for your next project, but the problem is that they're green and not quite ready to use just yet.
As a general rule of thumb, you should let your live edge slabs air dry for 1 year per every inch thick they are. Then, they should be kiln dried. You'll want them to be at most 20% moisture level when they are going in the kiln. When they're removed from the kiln, the ideal moisture level varies based on the environment the slab is going in. Typically this is 12% or less throughout the entire slab. For most of our wood slabs, we shoot for 8% moisture content.
If you do decide to build a dining room table or something else from a green slab, it will look fine, at first. The issue will arise after it's put in your home. As the slab naturally dries with time, your piece will begin to crack, warp, and ultimately become an eyesore of what was once a beautiful piece. Glued joints will begin to fall apart, and if you sold the piece to a customer, you'll likely be seeing a bad review shortly after this happens. These issues can happen as quickly as week 1 of being in a home or even as long as a year down the road.
So, now that we know the consequences of not drying your slabs properly, let's talk about how to dry them properly so your live edge furniture ages as it should.
Air Drying Your Slabs
Air drying is an essential first step to properly drying your slabs. At Lancaster Live Edge, we allow all of our slabs to air dry after they're cut for about 2 years. Allowing these to air dry prior to putting them in the kiln will help keep them from getting large cracks and warping from drying too fast.
After your slabs are cut, you'll want to immediately put them on sticks. This process is simple. We use small 1"x1" sticks in between each slab. We place these sticks every 16" or so across the face of the slab. When the slabs are then placed in storage as they air dry, the sticks allow air to flow through each slab so they all dry at the same rate.
These sticks also help support the weight of the slab. Some of the larger slabs we have weigh over 300lbs when they're cut. By supporting the slabs throughout the log with these sticks, and stacking them on top of each other, the weight and supports help keep the slabs straight and avoids warping. Below is a picture of green slabs that are being put on sticks prior to starting the air-drying process.
How To Know When The Slabs Are Done Air Drying?
We typically let our slabs air dry for 2 years, but many sellers do not. A general rule of thumb is that live edge slabs are ready to kiln dry when they reach 20% moisture level. This can be tested using a moisture meter.
If you're wondering how long this takes, the answer is that it will vary. Obviously, a thinner slab will dry much faster than one that's cut a few inches thick. A 2" slab dries in about 6 months, whereas a 3"+ thick slab will take much longer.
Kiln Drying Live Edge Slabs
After your live edge wood slabs are air-dried, you'll want to put them in a kiln for about 1-3 months. Assuming you don't have a kiln, you'll want to find a local shop that does. Many places that manufacture hardwood lumber, flooring, or other finished wood products will offer kiln drying services.
If you're using a third party to dry your slabs, you'll want to coordinate with them months in advance. Some places will have a backlog for their kiln and it may be months until they have room for your slabs.
After your slabs are kiln dried, it's important to verify their moisture levels. This will vary depending on where you're located. Where we're located in PA, we ideally want every slab to be 8-12% moisture level when we're building a table. The moisture level will vary at different parts of the slab, but the 8-12% range is what we shoot for.
How The Kiln Works
A wood kiln is essentially a chamber where air circulation, humidity, and temperature are controlled so that the moisture in wood gets reduced. When properly kiln dried, wood will get to a point where it won't have any drying defects.
A conventional kiln uses steam that's pushed through pipes and radiates heat into the chamber. The water within the wood is then converted to vapor and is released from the chamber with hot air. This type of kiln is not as efficient as a dehumidification kiln, so it isn't used as much anymore.
Dehumidification kilns are much more common. This type of kiln continuously recycles heat within the kiln. The water is condensed on the coils of the dehumidifier and removed as a liquid.
The Art Of Kiln Drying
Kiln drying lumber is an extremely delicate process. Every kiln and every species and cut of wood can dry a hair differently. At Lancaster Live Edge, we use an iDry Vacuum kiln. We have experts in-house at drying lumber. After all, we're the sister company to a sawmill that's been serving the east coast for several decades.
If you're looking for DIY drying for your slabs, being honest you're better to hire a professional. This process is extremely delicate. The larger (wider) of slabs you're working with, the more that can go wrong. You can get moisture pockets in your wood and even have your wood warp and crack to the point it's no longer usable. We've commonly heard customers with stories of drying their own wood. Some do things like sitting cinder blocks on the lumber to try to keep it from warping. At the end of the day, if wood wants to move, it will.
As with any art or craft, kiln drying slabs and lumber will require the right tools and equipment. At Lancaster Live Edge we're equipped with a professional kiln, as well as professional moisture meters and staff to ensure our lumber gets dried properly. The right equipment for this is not cheap, but it does help us ensure the quality of our furniture.
Finishing The Slab
After your slabs leave the kiln, they are ready to use! It may look a little uglier than you remember, but it'll look like it did when it was green after it's planed and sanded. You'll want to use a slab flattener to do this.
After you surface your slab, you'll want to use it in the near future. If you let your slab sit outside, or even store it against a wall once it's surfaced, it may warp with time. When it's surfaced the pours of the wood are opened back up, making it vulnerable until it's finished. This is typically only an issue if slabs are stored in humid locations or left outside for long periods of time after drying.
Have any questions or comments? We'll try our best to help! Drop them below in the comment box!
Nolan is one of the original members of the team at Lancaster Live Edge. Formerly, Nolan was the Marketing and Sales Manager at our company, and he also spent several hours a day building tables and custom furniture in our shop. Now, Nolan helps with our marketing initiatives. Prior to his time at Lancaster Live Edge, Nolan worked for years for his family’s custom home building company and has built everything from custom furniture to cabins to home additions.