Cutek Cutek

For outstanding protection of timber call

1300 1CUTEK

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Important Information:
Shrinkage and Movement

Shrinkage and Swelling

Shrinkage and swelling may occur in wood when the moisture content of timber is changed. Shrinkage occurs as moisture content decreases, while swelling takes place when it increases. Volume change is not equal in all directions. The greatest dimensional change occurs in a direction tangential to the growth rings. Shrinkage from the pith outwards, or radially, is usually considerably less than tangential shrinkage, while longitudinal (along the grain) shrinkage is so slight as to be usually neglected. The longitudinal shrinkage is 0.1 to 0.3%, in contrast to transverse shrinkages, which is 2-10%. Tangential shrinkage is often about twice as great as in the radial direction, although in some species it may be as much as five times as great. The shrinkage is species dependent and can be typically 5 to 10% in the tangential direction and 2 to 6% in the radial direction. Dried timbers that are coated with Cutek CD50 are less susceptible to dimensional changes because the deeply penetrating hydrophobic (water resisting) nature of Cutek CD50 minimises the free absorption and desorbtion of liquid and gas phase moisture therefore assisting with maintaining the dimensional integrity of moisture stabilised timbers.

Factors Affecting the Dried Appearance, and Dimensional Integrity of Wood

Factors that significantly affect the drying, appearance and dimensional integrity of dried timbers are: