For most consumer products built from hardwoods, the lumber needs to be dried prior to use. When a sawmill cuts logs into boards they are considered to be green (i.e. inclusive of moisture). Eventually, those boards are kiln dried down to a moisture content in the single digits in most regions. That is when hardwood lumber is considered to be acceptable for use.
In between the process of sawing the boards and kiln drying, hardwood manufacturers usually use air-drying or pre-drying techniques to help make the kiln drying process more efficient. The exact process depends on the species, thicknesses of lumber, time allotted and several more factors.
Whether air drying, or pre drying lumber, the goal is typically to get the lumber to a moisture content of around 30-40%. There are limitations and issues to deal with in both practices. For example, when air drying lumber climate and general exposure to weather elements has a significant impact on the lumber. Cold weather increases the time to dry and exceptionally hot and dry weather could severely degrade the boards while drying such as surface checking or end splitting.
Pre-drying hardwood lumber on the other hand raises other issues. Pre-drying is the process of introducing the use of fans in a controlled environment, such as a shed, to quicken the drying process. This protects the lumber from the elements and improves the overall circulation of air across the boards which accelerates drying.
Air drying and pre-drying are common practices in the hardwood lumber industry. But keep in mind they are each only one step in the process before the kiln drying process takes place. If you are looking for more information, or to better understand how we leverage both practices when we dry hardwood lumber, be sure to contact your Baillie Group sales representative for more specifics.
Tony C.
The Baillie Group