This movement was initially challenged by skeptics who claimed that moisture could be removed from the external sapwood, but not deep inside the heart of the timber. Thanks to a few kiln-drying pioneers in the log home industry, these initial assumptions are now changing. The process of kiln-drying lumber is the science of carefully controlling the extraction of moisture from wood at a rate which will not cause damage to the wood. When drying large dimensional lumber, a stack of cants is placed in a sealed building with the equipment necessary to control the conditions needed to season the timbers. Once the material is in the kiln, the temperature is slowly raised to an eventual 170 degrees Fahrenheit.
Heated air is used primarily to speed up the evaporation of the moisture in the wood.
Warmer air will absorb a greater amount of moisture as it flows over and around the green lumber. Large fans circulate the heated air and change the direction of the air-flow at regular intervals to help maintain a consistent drying rate throughout the kiln. The moisture laden air is removed from the kiln by way of an automatic ventilation system and large dehumidifiers. The drying rate of the timbers is carefully monitored because the outside perimeters of the cants naturally tend to dry faster than the centers. This adds moisture to the outside portions equalizing the moisture throughout the wood.