Lumber Care Tips from J. Gibson McIlvain
As a lumber importer, J. Gibson McIlvain sources lumber from many areas around the globe. Each geographic area and particular lumber mills all have their unique M.O. While most imports are dried to 12-15% moisture content (the European standard), domestics can sometimes be air dried to anywhere from 10 to 25% moisture content. While various handling methods are employed, depending on the state in which we receive the lumber, the same basic process can be followed for just about any board. One major area of variation will be the total time from the arrival of the lumber in our yard to the time when it’s ready to be sold and shipped off to a jobsite.
In both our Maryland and our Connecticut lumber yards, the back corners are dedicated to the air-drying process. Just about every stick of lumber we get in spends some time stacked and stickered in those back corners. Stickers are basically spacers that allow for air flow around the entire board, providing opportunities for even release of moisture. As you might expect, the wetter the wood is, the longer it will need to air dry. Typically, we paint or wax the ends of the boards in order to slow the release of moisture, in order to prevent checking and cracking. Because air drying is gentle on the wood, it’s a safe way to shed the majority of extra moisture.
Unlike kiln drying, air drying does not allow for the lignin to be “set,” so air-dried wood will not be as stable as kiln-dried wood. (The trade-off is that it will be softer and easier to work.) When wood is air dried, it comes to equilibrium with the local climate; sometimes this process takes only weeks, while other times it takes nearly a year. If kiln drying will be done, air drying helps prepare the wood for that next step.
Once the wood has achieved acclimatization, it can safely begin the kiln-drying process in order to help it attain a moisture level of 6-8%. The kilns we use at J. Gibson McIlvain Lumber are quite environmentally friendly, since the boilers are heated by offcuts and dust generated by our own mill. The amount of time and temperature used in kiln drying is dependent on the species and its density. Denser wood may need more than a month, while some species may take only 2-3 weeks. Slow heat up and cool down are key to avoiding hardening or other forms of damage.
Improper drying often results in damage that isn’t obvious until you’re already knee-deep in your project. We make sure to take our time and dry all our lumber properly so our customers can avoid the kind of hang-ups and extra expenses that crop up when their lumber misbehaves.