Wood Density

What is Wood Density?

The density of wood describes the ratio of its mass to its volume and is given in kilograms per cubic meter (kg/m³). It indicates how heavy a specific volume of wood is and plays a key role in assessing properties like strength, hardness, and insulation capacity. Wood density varies depending on the wood type and moisture content and is an important factor in selecting wood for specific applications such as construction or furniture.

Calculating Wood Density

Density is calculated by dividing the mass of the wood by its volume:

Since wood absorbs and releases moisture, density can fluctuate based on moisture content. Therefore, bulk density is often reported both in an absolutely dry state and at a defined moisture level (e.g., 12%), which is frequently used for technical calculations.

Impact of Density on Wood Properties

Bulk density influences key material properties:

• Strength: Hardwoods like oak, with high density, are more resistant to pressure and abrasion, while softwoods like spruce are lighter and softer.
• Thermal Conductivity: Lower density often results in better insulation, as more air pockets provide insulating properties.
• Workability: Lighter wood is often easier to work with and well-suited for carving or lighter structures.

Wood Density vs. Mass Density

In addition to wood density, there is mass density. This term refers to the density of the material itself, excluding any pores or voids, and is often used for precise scientific studies. However, since wood is a porous material, mass density significantly differs from density, which includes air spaces and voids.

In Summary - Simply Explained

Density indicates the ratio of mass to volume in wood and directly affects its strength and insulation capacity. True density, on the other hand, describes the density of wood without voids and is less commonly used in practical applications.