Determining wood moisture content of is a key factor at all stages of the manufacturing process. This is a critical operation to obtain quality products, reduce raw material waste and minimize problems in the use of finished products. The objective of this project was to develop procedures for assessing the moisture content of appearance wood during each processing stage, that is, from the sawmill to the kiln, from the kiln to secondary processing facilities and from these facilities to the end-user.
Using reliable, accepted and proven moisture content assessment procedures will benefit manufacturers and their business relations. Client-supplier business relations (internal or external) are founded on mutual trust and moisture content measurement is one of the main causes of disagreement. In addition, poor assessment of the moisture content of semi-finished or finished products can have costly consequences for business.
Part of this report focuses on basic concepts because it is critical to understand certain physical properties of wood in order to interpret moisture content measurements. These properties include moisture in wood, equilibrium moisture content, moisture gradient and fibre saturation point. It is also important to understand how variations in wood moisture content affect the dimensional stability of wood products. This calls for a discussion on shrinkage and swelling.
Another section of this report describes the three main methods for assessing moisture content: the oven-drying method, the use of DC-resistance moisture meters and the use of dielectric moisture meters, and explains the various factors affecting each method. Basic procedures for each method are presented and adapted to account for the condition of the lumber (green or dry, rough or surfaced, stacked or unstacked, stickered or solid-stacked, etc.) and the stage of the manufacturing process (lumber stacking facility, kiln, processing mill entrance, shipping/reception docks, finished products, etc). Finally, the report deals briefly with basic statistical and sampling concepts.