Introduction: Kiln Dry Lumber at Home
Kiln drying your own wood at home can be a great way to sustainably harvest the materials around you, and dry it fast enough to build furniture with. If furniture is made with wood that is too wet, it will continue to dry and crack, possibly ruining the piece. This instructable takes you through the process of raw wood in the spring, to dry lumber in the fall. You can do this with any kind of wood.
Step 1: Mill Up Your Wood
Finding rough timber and logs to mill is a lot easier than you may think. There's always someone around that's trying to get rid of a fallen tree or wants to take down a dead tree. Calling around to local tree trimmers and arborists can lead to some great opportunities. These people make a living with trees, and if you can offer them a fair price for a log, they'll often choose to sell it because it saves them the work of disposal, or processing it into firewood. Put an add in the paper, call your local city or municipality and ask about who deals with downed trees. The list goes on and on, but you can definitely find something. The term "windfall" comes from just that, wind storms can mean lots of wood.
Once you've gotten the wood, local sawyers are plentiful in most areas, and many will bring their portable sawmill to you for a very reasonable rate. I pay $100 an hour here, and a good sawyer can do a lot in an hour. Worth their weight in gold, these hardworking folks are a woodworkers dream come true, and they often have a stock of amazing, local woods for sale.
You can also choose to mill it yourself with a chainsaw, which I partially do sometimes depending on the log. If you choose to do this, read up, and follow all the safety precautions of those tools. And like anything in woodworking, protect your eyes, ears and lungs.
Step 2: Wood & Moisture
If you don't seal the end grain of your logs and timbers, they will crack and split as moisture is perspired. The end grain needs to be sealed up with a material that will close up the open pores of the wood. I often mix 50/50 wood glue and water then saturate the ends several times. You can also use paint or wax. These logs all started off at a pretty normal 32 percent moisture content.
Step 3: Air Drying
Start off by air drying your wood for a few months to shed the first bit of water naturally, maybe a loss of eight to ten percent. Stack the wood up with plenty of spacers, or stickers, to allow for good airflow, and I like to put a piece of plastic on the ground under the wood to keep the humidity from the ground from effecting the lumber. I bind the wood with tie downs to minimize cracking and twisting, and I build a temporary plastic roof to keep off the rain. Place it in a location with good prevailing winds, it makes a big difference.
Step 4: Build the Kiln
After a few months, bring the wood indoors and finish the drying. To build the kiln lay poly (clear plastic roll) on the ground and then build a frame with 2x4 studs on top of it for the lumber to rest on. Leave enough space to have a standard household dehumidifier at one end, and a small fan at the other.
The fan circulates the air to even out the drying. I designed mine to pull air from below, then blow the air down a plastic tube to the other end. This way I know there's no stagnant air or dampness trapped in the kiln. This one is 20 feet, or 6 meters, long. The dehumidifier is also trapped inside the kiln and is set to maximum. This model has a hose that runs out of the kiln and fills a bucket.
The kiln is built around the stacked and bound lumber over a light wooden frame that carries the plastic. All seams need to be sealed with vapour barrier tape to hold the moisture in. I cut a few small access holes to control the dehumidifier and to test the woods moisture content in various places. Tape up these holes after you use them. The wood remained in the kiln for about 4 months and reached an average of 8 percent. This is mostly 2" thick arbutus, also called madrone.
Step 5: Using the Wood
Bring the wood into your workshop and allow it to acclimate for a few weeks, then start processing it. You can see here that the 1" thick material is below 7 percent, excellent for making furniture.
Step 6: Making Furniture
Using this unique wood often presents the opportunity to really showcase a unique piece of wood that you can be proud of harvesting in a sustainable manner.
Thanks for taking the time to read through this instructable, now get out there and save some logs!