NOTES

• trees:

  • Natural wood is categorised as either hardwood or softwood
  • Most hardwood and softwood trees have characteristics that help us recognise them
  • Both types can be grown and harvested responsibly in managed forests
  • This makes wood a sustainable and biodegradable resource
• Natural wood:

  • A useful and versatile material
  • Aesthetically pleasing
  • A good insulator
  • Durable and tough
• Felling:

  • A tree is ‘felled’ when it is cut down
  • Traditional methods of felling used saws and axes
  • Chainsaws are used in modern felling
  • Agricultural logging uses machinery with large chainsaw attachments. These can fell, de-branch and log a tree in one swift action
• Softwood:

  • Softwood comes from coniferous trees
  • Most coniferous trees have needles, are evergreen, and they keep their needles all year round
  • Softwood trees grow faster than hardwood trees making it relatively cheap and readily available
  • The grain is wider making it more absorbent
• Hardwood:

  • Hardwood is sourced from deciduous trees
  • Deciduous trees drop their leaves in the autumn and new leaves grow in spring
  • Hardwood is slower growing and is therefore more expensive
  • Sought after for its variety of colours and grains, it has good aesthetical and physical properties
  • It has a closer grain, making it more dense and hardwearing
• Working properties:

  • Strength – the amount of load or compression it can withstand
  • Toughness – absorption of energy through shock before splitting
  • Elasticity - will it return to shape after being compressed?
  • Hardness – how resistant is the surface? Will it survive scratches, knocks and abrasion?
• Useful hardwood:

  • Hardwoods are used in wide range of applications
  • Ash is very tough, but also flexible and shock resistant
  • Beech is tough and very durable with a fine finish
  • Oak is tough, hard and durable with a variable grain
• Ochroma pyramidales (Balsa):

  • Balsa wood is a soft and lightweight material
  • Balsa trees are very fast growing which gives the wood a coarse, open grain
  • The living tree has large cells that fill with water – this gives the wood its spongy texture
  • Strong in relation to its weight and density, Balsa is used for lightweight, rigid structures such as prototypes, model bridges and model aircraft
• Desirable hardwood:

  • Mahogany is sought after for its durability, colour and aesthetics
  • Its deep rich reddish brown hue gives beauty and warmth to furniture, musical instruments, boats and interior panelling
  • Unfortunately man’s desire for mahogany has increased the destructive and illegal logging trade
• Useful softwood:

  • Softwood is cost effective and readily sourced, making it an ideal choice for the construction industry
  • Pine is lightweight and easy to work with
  • Larch is durable, tough and has good water resistance
  • Spruce has a high stiffness to weight ratio
  • Cedar contains natural oils which offer natural water resistance
• Tone wood:

  • Some woods possess tonal properties that make them ideal for use in stringed instruments
  • Spruce is commonly used in violins, piano and guitar families of instruments
  • Its high stiffness to weight ratio makes it ideal for the soundboard, which transmits the vibrations from the strings
  • Mahogany is used for necks and sides of acoustic guitars and sometimes for the body of electric guitars
• Manufactured boards:

  • These can be made from sawmill scraps, recycled wood, low grade timbers and even sawdust
  • Wood pieces are bound together with adhesives to make man-made / manufactured board
  • Manufactured board can be susceptible to moisture
  • Boards are rigid, stable and supplied in large sheets
• Common boards:

  • Medium density fibreboard or MDF - Very dense board which makes it tough, Its smooth surface makes it suitable for veneers and finishes
  • Chipboard or particle board - Good compressive strength, edges chip easily
  • Plywood - Made up of alternative rotated layers of glued wood veneers, Available in various forms including marine ply for greater water resistance
• Veneers:

  • can enhance the look of manufactured board
  • Veneers may be made from real wood, a man made finish or plastic
• Knotts:

  • Natural timbers can have natural defects
  • The most common natural defect is a knot
  • Softwoods such as pine, larch and cedar can also seep resin at the knot