What causes wood to shrink & how does it affect quality?
All woods are hygroscopic, that is, it will absorb or discharge moisture to attain equilibrium with the surrounding atmosphere. Typically, in the Australian climate, it is common to experience a loss of moisture. The loss of moisture content from the wood, results in the shrinkage of wood due to the loss of water. This can be interpreted by some that it weakens the overall quality of wood. However, in reality, the opposite occurs. In fact, seasoned timber (dried timber) contains properties that make it superior to wet timber. Listed below are some of the advantages:
Strength: The drying of timber results in increased strength, bending strength and stiffness.
Hardness: As the plant cells become more compressed, it results in a structure that is harder and more resistant to bumps and other damage.
Weight: The decreased water content considerable reduces the weight of timber.
How long does it take for timber to dry?
Most of our timber pieces are kiln-dried to speed up this process before we pack and ship out our products to you. However, dried timber will still retain a small % of moisture and will continue to dry when being built and used. Timber dries from the outside to the centre, this is a lengthy process which can take up to 6 years to reach its equilibrium moisture content (EMC).
What causes wood cracks?
When our timber is first sourced from New Zealand and other sources around the world, much like the human body, it is composed of a considerable amount of water, this can range anywhere from 40% to 400% of the log, in other words some timber logs can hold up to 4 times its weight in water! During this manufacturing process the timber is further air dried, stained and treated to ensure that our swing sets are safe and secure for creating our play sets. However, whilst this process drastically reduces the water content of our timber, it is not completely removed.
As a result, the wood drying process continues well after being installed in your backyard. The drying process generally results in the shrinkage of wood, as the wood shrinks, checks may begin to form in the exterior of the timber. This is recognised and accounted for by timber framers and engineers as a process which doesn’t compromise the integrity of the wood.
