Should you kiln dry, or air dry your lumber? Well that depends, there are some definite benefits to both. You will want to know your customer and their needs before you decide for sure. From the perspective of the lumber yard you have the benefit of getting the product to market much sooner if you kiln dry. This can prevent cash flow problems because you are getting a return on your lumber or log investment much more quickly, and it can help you meet deadlines. Moving the inventory quickly will also free up space in your lumberyard for new product. Or if you are using the lumber yourself for a project, then you can get to work much sooner if the lumber is kiln dried. Another benefit is that a kiln can set the pitch even if the lumber is already dry. The high temperatures in a kiln can also kill insects and their eggs. A kiln can get the moisture content down to levels below that of air dried lumber. You want to be careful with this one though because kiln dried lumber will actually re-absorb moisture from the ambient air. If the lumber is not stored in a climate controlled building it will quickly return to its equilibrium. Because of this re-absorption of moisture, professional floor installers allow the wood to reach equilibrium in your home for a minimum of 24 hours prior to laying the flooring in place.
As far as proponents of air drying or shed drying lumber they are growing by leaps and bounds. Many small shop wood workers are discovering the benefits of working with non-kiln dried woods. Many believe that you can actually feel the difference. Kiln drying speeds the process of drying the wood by subjecting the wood to heat and pressure so that it rapidly pulls the moisture out and weakens the cell walls – this can be especially problematic in lumber thicker than 8/4. The wood fibers are also weakened and they no longer have that glow of life from the cell. Air drying lumber preserves the intrinsic beauty of the wood where it actually glows. Whereas kiln dried material can have more of a, “stone-like” ambiance. The kiln drying process also diminishes the intensity of the color of the wood, and the sublte color changes of the grain – up to 20% in some species. For this reason many high end, one of a kind, furniture makers only choose air or shed dried material. Air dried wood is less brittle, and because it is already at equilibrium, it isn’t going to take on more moisture and twist on you later which can be true of kiln dried material as it returns to equilibrium. Turners and benders frequently want air dried material as well. For those who believe that good furniture cannot come from air dried material, I would challenge you to look in your local antique store, or at Grandma’s house. In the end it boils down to your personal preference, (or business needs), as there is a good case to be made on both sides of the equation. Happy drying!