* Rapid growth: When a tree grows quickly, the wood fibers may not bond properly, leaving weak spots that can later develop into shakes.
* Environmental factors: Harsh weather, drought, or insect infestations can stress the tree, leading to internal cracks.
* Mechanical damage: Branches breaking off or the tree being hit by something can also cause shakes.
Here's what distinguishes a shake from other wood defects:
* Direction: Shakes always run parallel to the grain of the wood, unlike checks which run perpendicular.
* Depth: Shakes are usually deeper than checks, sometimes extending all the way through the timber.
* Appearance: Shakes often look like a split or crack that extends across the width of the timber.
Impact on timber:
* Strength reduction: Shakes weaken the timber, making it less strong and prone to breaking.
* Appearance: Shakes can be visually unattractive, especially if they are large or numerous.
* Durability: Shakes can make timber more susceptible to decay and moisture damage.
Uses:
* Lower grade timber: Shakes typically downgrade the timber and make it unsuitable for structural applications or high-quality furniture.
* Specific applications: In some cases, shakes can be used for specific applications, like cladding where their appearance is less of a concern.
Note: Shakes are a natural part of wood and are not always a deal-breaker. The severity of the shake and its location will determine its impact on the timber's suitability for different uses.