06 – Drying of Pith

When wood is used as a construction material, whether as a structural support in a building or in woodworking objects, it will absorb or expel moisture until it is in equilibrium with its surroundings.

Moisture affects the burning process, with unburnt hydrocarbons going up the chimney. If a 50% wet log is burnt at high temperature, with good heat extraction from the exhaust gas leading to a 100 °C exhaust temperature, about 5% of the energy of the log is wasted through evaporating and heating the water vapour.

For some purposes, wood is not dried at all, and is used green. Often, wood must be in equilibrium with the air outside, as for construction wood, or the air indoors, as for wooden furniture.