Composition of Wood

Table of contents:

The atomic composition of dry wood is approximately:

• 50% carbon
• 6% hydrogen
• 44% oxygen
• traces of inorganic elements

This consists of:

• 40-50% cellulose
• 20-35% hemi-cellulose
• 15-30% lignin
• also small extractives (resins, tannins, fatty acids) which matter more for softwoods

Wood also contains water (about 20% for air dried wood), which absorbs heat on evaporation.

When burned, it wood contains roughly 80% volatile matter and 20% fixed carbon (plus water and incombustible ash).

References:

Rowell, Roger M.; Pettersen, Roger; Tshabalala, Mandla A. 2013. Cell wall chemistry. In: Rowell, Roger. ed. Handbook of wood chemistry and wood composites, Second edition. Boca Raton, FL: CRC Press: 33-72. Chapter 3.