The Amount of Air in Oven-Dry Wood

Wood contains air and water as well as wood substances. Wood, when oven-dry, contains only air and woody tissue. The oven-dry density of any species is a direct reflection of the amount of space occupied by wood tissue. Wood densities can vary from 50 kg m with balsa (Ochroma lagopus) to 1400 kg m with lignum vitae (Guaiacum officinale), although most commercial species have densities between 350 and 800 kg m. The proportion of air space to total wood volume can be estimated from the oven-dry density of the timber. Consider a timber having an oven-dry density of 500 kg m . A cubic metre of such a timber would contain 500 kg of woody material whose density is roughly 1500 kg m . This means that the wood substances occupy some 0.33 m leaving 0.67 m as air space, i.e. two-thirds of the volume is air space. This calculation emphasizes the porosity of most dry wood. 

Maximum moisture content and estimation of basic density 

The maximum moisture content for a wood can be estimated easily. In a timber having a basic density of 300 kg m the oven-dry cell tissue (density 1500 kg m ) 

In the case just examined the basic density is, as expected  

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