Wood

• what are the 3 categories of wood

  • soft woods
  • hard woods
  • manufactured boards
• soft woods are


  timber from coniferous trees
• hard woods are


  timber from deciduous trees
• manufactures board are


  boards made from wood pulp, chips or layers
• woods can either be

  deciduous or coniferous
• deciduous trees have


  broad green leaves which shed in autumn
• coniferous trees have


  needle type leaves which stay on the tree all year round (evergreen)
• woods are


  fibrous materials made up of plant cells and resins - the main structure is cellulose held together with lignin
• wood is


  hygroscopic - gives up moisture in a dry environment and takes in moisture in wet (unstable)
• trees grow from


  the outside inwards - the weakest wood is just inside the bark =
• what is trees re-growing known as

  coppicing
• what needs to be done to wood before it is ready


  seasoned
• what is seasoning wood

  when the wood is dried so all the moisture is removed
• how is wood seasoned

  can be air dries (takes years) or kiln dried (takes days)
• are hardwoods or softwoods more expensive

  hardwoods - take longer to reach maturity (can be sold) than softwoods
• hardwood is


  more durable, higher quality and more expensive
• types of hardwoods

  • oak - durable, hardwearing, attractive
  • beech - small grain, hygienic, durable
  • teak - water repellent, durable
  • ash - springy, strong (compression)
  • mahogany - hardwearing, attractive
  • walnut - dark, dense, tight grained, attractive
• soft wood takes 25 years to reach maturity meaning it is cheaper
• soft wood is grown geographically closer to the uk - cheaper
• softwood is more readily available than hardwood
• softwood comes in many different forms:

  • rough sawn treated - roughly presented for outdoor use
  • rough sawn - roughly presented for non visible sections in home
  • planed - smooth surface for where it is visible
• types of softwoods

  • yellow pine - affordable, readily available
  • spruce - common building material
  • cedar - fragrant, strong, attractive
  • douglas fir - strong, workable
  • parana pine - straight grain, uniform, workable
• manufactures boards are made by using an adhesive to hold fibres, chips or layers of natural wood together
• the adhesive used is

  urea formaldehyde
• types of manufactures boards

  • MDF (medium density fibreboard) - large sheets, cheap
  • plywood - large sheets, strong, attractive
  • chip board - good compressive strength
  • stirling board - large sheets, cheap
  • flexi-ply/MDF - flexible, large sheets
  • aero ply - strong, flexible, lightweight
  • conti board - chipboard but heatproof and wipeable surface
• common wood storage forms

  • planks
  • beams
  • square and rectangular section
  • dowel
• wood is cut down for our use which is causing deforestation and the production of carbon during the process of making the product suitable for the user
• trees provide

  • conversion of carbon dioxide
  • provide building materials
  • pulp is used to make paper and card
  • provide food for humans
  • provide shelter
  • can be burnt for fuel