Specific words and the terminology used does actually matter. Even though those reminders may be useful, not all words are as useful as we might imagine. Communication problems frequently arise when people use diverse definitions of the same terms. “Kiln-dried lumber” is one of those words loaded with a variety of meanings which is commonly used throughout the lumber industry. In addition to utilizing that phrase, you might wish to inquire as to what specific moisture level the lumber was kiln-dried to or to describe the desired moisture level for your wood purchase based on what you may have learned in Part 1.
How the Air-Drying Process is Conducted
At J Gibson McIlvain Lumber Company, our standard procedure is to evaluate the moisture levels numerous times throughout the pack of exotic timber as it enters our lumber yard. We don’t just want to measure the outside layer, but also the boards buried in the pack’s middle. The three distinct readings are then recorded on a form and transmitted via our Vision Tally System, allowing us to maintain incredibly precise and thorough records of our inventory. The lumber then travels to our air-drying yards to go through the typical acclimatization procedure.
Another element that unquestionably influences the lumber’s moisture level is the rough travel inside shipping containers, which the air-drying stage aids in recovering from. We lay the lumber on blocks with stickers propped between each board to encourage airflow throughout the stack, allowing the lumber to acclimate to our East Coast climate in North America. It is impossible to overstate the importance of those initial weeks spent letting the lumber rest and adjust to our local climate. Since our local climate is dryer than the origin of most exotic lumber – or even the shipping container in which it made its overseas journey – it will not only allow the moisture levels of each board to even out, regardless of where the board was located in the pack, but it will also promote a lower moisture level overall.
Based on the type of lumber and its moisture level when it arrived in our lumberyard, we carefully calculate the time we provide for this air-drying procedure. We take our time because we understand that hurrying lumber into the kiln might ultimately cause instability for your project later on.
What Takes Place During Kiln-Drying
Note that the cell walls of lumber that has already undergone kiln drying have already been toughened throughout the process, improving the board’s overall stability. At the same time, as the moisture content of the lumber is further decreased to less than 8%, those cells will dramatically harden and the timber will become even more stable. We believe that gradually taking lumber down to where the cell walls will be set is a significant benefit, allowing for slower future shedding and absorption of moisture, preventing long term cracking and other types of damage. Normally, when lumber exits our kilns, it will start to take on moisture in keeping with our climate; however, the careful, thorough kiln drying will minimize that future water intake.
Although thorough re-drying will increase your costs, it will pay off in the form of sturdy, high-quality lumber if you practice quality control that includes these crucial procedures.