Timbers

• When selecting timbers we need to ask ourselves these questions:

  • How do they look?
  • What are they commonly used for?
  • How can they be manufactured?
  • How do they perform in use?
  • What makes them unique - are they the most durable, the lightest etc?
• When selecting a timber-based material, there are many different types to choose from. Hardwood and softwood are types of timber that come from many different trees. 
• Manufactured boards such as medium-density fibreboard (MDF) are man-made from recycled material and other boards such as plywood are man-made from layers of wood.
• Chipboard 

  man-made sheet material, made from small chips of timber glued together to produce a dense sheet.
• MDF


  small timber fibres that are mixed with wax and resin. They are heated and compressed so that a flat, usable sheet is produced.
• Plywood is made by gluing at least three layers of sheet timber together at right angles to each other - this is called laminating. Plywood is considered to be a strong board as the grain of the timber sheets are glued together in different directions.
• Aesthetics relate to the way a material looks, and each example of timber has a different pattern on the grain and texture.
• We can alter the appearance of timber through different methods:

  • staining
  • varnishing
  • oiling
  • waxing
  • painting
  • laminating
• When a tree is chopped down for timber, there is a cost to the environment. Trees are vital for our survival as they absorb carbon dioxide (CO2).
•  Some softwoods are readily available due to the fast-growing nature of the tree. Hardwood, on the other hand, grows considerably slower and is therefore much more expensive.
• Manufactured boards vary in price depending on where they are bought and how many are bought at once. Some timber is sold at a price calculated by volume. The price per metre cubed (m3) is the method of working out the value. If the price per m3 is known, then the calculation to work out the cost starts with working out the volume of timber that is needed.
• Forces that can act upon a material:

  • tension - a pulling force
  • compression - a pushing force
  • bending - forces at an angle to the material
  • torsion - a twisting force
  • shear - forces acting across the material
• Fill in the blanks:

  A) Compression

  B) Bending

  C) Tension

  D) Torsion

  E) Shear

  
• Timber has good tensile strength and compressive strength due to the fibrous structure. Timber, if untreated, does not have good bending qualities and often snaps when bent.
•  If timber is soaked in water or exposed to steam, it can become more flexible. Slots can be cut along the inside face of the timber to be bent allowing for the inside face to cope with the compressive force - this is called kerfing.
• Fill in the blanks for the steps of kerfing:

  A) Cutting

  B) Gluing

  C) Compressing

  
• To reinforce or strengthen timber there are a few methods to choose from. Plywood is strengthened by having the timber glued at right angles to each other.
• Timber is easier to bend along the grain, but when another sheet of timber is glued at right angles it becomes hard to bend in any direction because the grains are at right angles to each other
• When considering the ecological and social implications of using timber, the term ‘deforestation’ is often used. Deforestation is when a clearing is made by chopping down trees. 
•  It is possible to manage deforestation through responsible management of the forests. If more trees are planted than are cut, it is possible to minimise the impact.
• Supply and demand can cause issues for forest management. If the customer demands more timber because of an increase in purchasing, a forest management organisation could struggle as trees will take time to mature.
• A way to combat deforestation would be to use more manufactured boards or recycled timbers
• Whenever environmental impact is to be reduced, the term ‘the 6 Rs’ can always be called upon to ensure an in-depth analysis has been done. The 6 Rs can be considered by the designer, the manufacturer and the consumer to reduce that negative impact on the environment.
• Fill in the blanks about the 6rs

  A) Rethink

  B) Reuse

  C) Recycle

  D) Repair

  E) Reduce

  F) Refuse

  
• Reduce - Can the amount of timber used be reduced? Can the timber be bought locally to reduce product miles?
• Reuse - Can the timber be reused for another purpose once a product is finished with?
• Recycle - Can the timber be disposed of correctly so that it can be recycled to produce another material like chipboard or MDF?
• Rethink - Can the way a product is made be redesigned so that less timber is used?
• Refuse - Refusing to use hardwood can be a consideration; could a wood stain be used on softwood instead?
• Repair - When a product is broken, can it be repaired rather than discarded?
• Hardwood trees take a long time to grow, around 60 years (sometimes up to 100). Hardwoods include ash, balsa, beech, mahogany and oak. Softwood trees take around half the time, 25 to 30 years and include larch, pine and spruce.
• The Forest Stewardship Council (FSC) is an international organisation that promotes responsible forest management.
• if the timber has been freshly cut, it is sold as ‘green’ timber due to the high water content. If the timber has been dried out before being sold, then it has been ‘seasoned’. 
• Many toys are made from timber, but the correct timber must be chosen with care, as the toys need to be tough and hard wearing. This is why beech is used
• Flat-pack furniture is often made from a material called chipboard. Chipboard is made from small particles of timber and dust that are bound together with a resin. Chipboard is compressed so that it is dense and flat.
• Chipboard needs to be coated so that moisture can’t get to the wood fibres; otherwise, they will absorb the water, causing the chipboard to swell.
• Chipboard is normally covered with a polymer laminate - the polymer might have a pattern on it to look like an expensive hardwood or could be white.
• If planed timber is bought, the price will be higher because of the care taken to process the length of wood. PSE is a term used to indicate that the timber has a ‘planed square edge’. 
• Hardwood and softwood are normally sold in lengths called planks, boards or mouldings. Planks and boards refer to the proportional dimensions of the timber, whereas moulding refers to a decorative patter
• Veneer is the term used to describe a thin sheet of timber, usually made from an expensive hardwood. Veneer is cut in the same way that a pencil sharpener works