Why Measure the Moisture Content of Wood?

Wood is used in modern furniture and many industries; processing is decisive. Moisture content is a key parameter—what level suits wood best?

1. What Is the Moisture Content of Wood?

In China, wood moisture content is defined as the percentage of the oven-dry weight accounted for by the water present.

Calculated on the dry-weight basis, the value is the absolute moisture content (W, %). Formula:

W=(Gs-Ggo)/Ggo×100% where: W—absolute moisture content; Gs—weight of wet wood; Ggo—weight of absolutely dry wood.

2. The Importance of Understanding Wood Moisture Content

Why do wood products—doors, flooring, furniture—crack and deform after sale? How can these losses be reduced?

Once manufacturing is complete, intrinsic quality depends mainly on moisture content and drying stress; wood is least likely to crack or deform at equilibrium moisture content in use.

Distributors should also test product moisture to understand quality and choose reliable manufacturers; any quality-conscious manufacturer tests its products' moisture.

In quality procurement, growing expertise has focused attention on moisture content; foreign buyers have long valued this indicator, as exporters well know.

3. Is the Wood Dry? How Dry Should It Be?

Wood left in an environment tends toward its equilibrium moisture content (EMC): above it, wood sheds moisture and shrinks; below, it absorbs and swells. Annual EMC averages 15.1% in Guangzhou and 11.4% in Beijing—11%-dried wood suits Beijing but swells in Guangzhou. Dry appropriately, not maximally.

4. Wood Equilibrium Moisture Content:

The stable moisture wood finally reaches through adsorption or desorption under a given atmosphere is its equilibrium moisture content.

5. Laboratory Methods for Measuring Moisture Content:

Methods include drying, electrical, dry distillation, titration, and hygrometry; wood processing usually uses the drying method.

Dry a representative 10-12 mm along-grain specimen (free of knots, decay, or insect damage; taken 250-300 mm from the lumber end) to absolute dryness: weigh immediately on a 0.01g, ≥200g balance (G), dry at 103±2°C for ~6 hours, then reweigh every 2 hours until constant (Go). Then W = (G-Go) / Go × 100%.

Weigh thin specimens immediately after oven removal, or seal them in plastic bags to prevent evaporation. The drying method is accurate and reliable without moisture-range limits, though destructive and time-consuming—the fundamental standard method; the formula gives absolute moisture content.

VicoMeter moisture analyzers provide you with optimal moisture measurement solutions. Feel free to contact us.