topic 3&8: performance and processing of woods

• Grain pattern- wood grain refers to the alignment, texture and appearance of wood fibres
• Grain direction - the direction in which a greater number of fibres are oriented. Also shows the longitudinal and vertical axis of the trunk.
• Surface defects- lines or planes that divide a substance into sections, each have a distinct orientation but the same crystalline structure.
• Warpage- the extent or result of being bent or twisted out of shape, typically as a result of the effects of heat or damage.
• Shrinkage - the decrease in volume overtime due to moisture loss from the level of humidity in the atmosphere.
• splitting - being broken or divided into parts/ segments
• joining - linking or connecting two different components
• forming - combining different parts or making something into a specific shape or form
• Stream bending is the process of soaking a piece of wood in hot water at boiling point for a certain period of time in a steam box, softening the fibres to make it stretchier.
• Laminating is the process of layering materials to increase strength.
• Machining Qualities refers to how easily a material can be processed, cut and shaped in a machine.
• Resistance to Decay is how well a material can withstand the exposure to rotting and decay.
• Moisture Resistance is Wood's ability to handle exposure to moisture and prevent decay, warping, or damage due to water absorption.
• Toxicity is the potential of wood or wood treatments to release harmful substances that can be hazardous to health.
• traditional joining methods are comb joint, dovetail joint, housing joint, half lap joint, dowel joint, and mortise and tenon.
• Comb joints are used to form boxes and carcasses – they are also known as finger joints 
• • Prized for their strength and aesthetics, dovetail joints are ideal for cabinets and drawer construction
• Half-lap joint is a versatile joining method that is easy to construct
• • Dowel joints are a quick, simple and effective method to join a variety of materials
• • A heavy duty joint used in load bearing timber frameworks is mortise and tenon
• performance characteristics of wood include: grain pattern and direction, warpage shrinking splitting, machine qualities, resistance to decay and moisture, toxicity.
• The structure of wood grain can affect workability and cost
• • Many hardwoods, such as mahogany, oak and olive wood, are prized for their decorative grain pattern 
• Beech has tight and fine grain which makes it easy to turn
• The end grain is the pattern which can be seen at the end of a piece of wood
• The structure of wood can be explained by considering the biology of a tree
• Wood fibres are made from hollow straw-like cells (tracheid) which are held in a lignin
• Tracheid carry water and nutrients to and from the roots and leaves
• Straw-like cells makewood strong along its length 
• wood will always split in the direction of the rays
• When the grain gives natural wood different physical properties in different directions, it is an anisotropic material
• MDF and Plywood are not anisotropic materials