Wood

• Stock Forms


  • Rough sawn
  • Planned square edge (PSE)
  • Planned all round (PAR)
• PSE


  Planed on 2 sides
• PAR


  Planed on 4 sides by 3mm each side (6mm each axis)
• Tree to timber


  1. Rough sawn timber sold after felled

  2. PSE and PAR requires extra machinery to make edges square and achieve small finish

  3. Planer thicknessers trim rough sawn timber into PSE and PAR
• Rough sawn timber


  Cheapest stock form, surface rough from industrial saws, used in construction
• Planed timber


  Prepared using planer and thicknesser, material wasted away little by little, achieves a 90 degree edge on one or more sides
• PSE timber


  1 square edge 3mm planned
• PAR timber


  Square on all sides, 3mm planned (makes timber smaller and smoother) from each surface
• Natural Timbers


  • Majority, sold as boards, square sections, consistency and convenience, dowels and mouldings are machined before being sold
• Mouldings


  Machined profiles, made for functional and aesthetic purposes, decorative for interior and products, used for skirting boards, picture frames, beading, balusters, spindles
• Manufactured boards


  • Chipboard
  • LDF/MDF/HDF
  • Plywood
• Softwoods


  • Fast growth, low cost, long straight shape, lightweight, less time seasoning than hardwoods, examples: pine, douglas fir, cedar, spruce, redwood, larch
• Pine


  Lightweight, straight grain, has knots, easy to work with, needs to be treated if outdoor use, most common woods in furniture and wooden flooring
• Redwood


  Tallest tree in the world, 3 metres a year, lightweight, soft, good strength to weight ratio, used for construction, decking
• Spruce


  Used in housing construction, instruments, cabinets, easy to work with, uniform texture, musical instruments
• Cedar


  High oil content, resistant to decay, moisture, weathering and insect attack, lightweight, easy to work with, knot free, fairly toxic-cause respiratory, stomach and kidney problems, used for boat building and outdoor panelling
• Larch


  Hard timber, fades grey when exposed to sunlight, high resin content clogs up cutting blades, used for veneers, fence posts, garden furniture, boats
• Fir


  Northern hemisphere, toughest wood, cheap, strong, large scale projects e.g. housing frameworks, cladding, difficult to treat due to density, high resin content, stable timbers, hold shape, swells, shrinks
• Hardwoods


  • Slow growing, need more land, expensive, aesthetic quality, dense, usually stronger, more durable, examples: oak, mahogany, jelutong, balsa, teak, beech
• Oak


  Mainly used in engineering-shipbuilding, architecture, tough, durable and hard wearing, resistant to rot when exposed to moisture, contains tannic acid which corrodes steel
• Balsa


  Natural cellular material with excellent stiffness-to-weight and strength-to-weight ratios as well as superior energy absorption characteristics, used for model aeroplanes, table tennis bats
• Mahogany


  Aesthetic, expensive, excellent stability, workability, beautiful grain, tall trees and stout so timber long, wide and defect free - ideal for veneers, certain are now protected by international trade laws
• Teak


  Naturally high in oils, outdoor products - furniture, boats - decay resistance, durability, toxicity, high resistance to acid + alkali
• Jelutong


  Low density, easy to work with, minimal grain, smooth surface, uniform appearance, softness, stability, dimensional stability, easy for carving, used for patternmaking, carving, toys, dowels, packing crates
• Beech


  Hard, tough odourless, resistant to abrasion, doesn't affect taste of food, close, straight grain, easy to work with, similar to ash, flexible, ideal for steam bending
• Manufactured boards - cabinets

  Veneers applied to top
• Plywood


  Strong in every direction so can't split along grain, uses lower grade hardwood and softwood veneers, uniform, hard, smooth, notice patches, some knots on surface not be tolerated in marine ply
• Marine plywood


  Water resistant hardwood layers are used, each layer thinner than standard ply, phenolic resin, a waterproof adhesive, bonds the defect-free layers together so it can withstand use in wet conditions
• Flexible plywood


  Aeroply and flexi ply formed into curved shapes, made from several birch veneers, flexi ply consists of a thin central veneer with two softer outers, both used for laminating or to cover curved frameworks
• Chipboard and MDF


  MDF made from fine wood dust particles, bonded with resin under pressure, chipboard larger chips, MDF perfectly smooth surface finish, uniform density throughout, ideal for CNC milling, whereas chipboard is less predictable, not very resilient without surface treatment but their durability is improved with veneers or a hard-wearing paint
• Flat pack


  Used extensively for manufacturing, standardised components or "knock-down" used for quick assembly and disassembly of products
• Hardboard


  Dark brown colouring, stable form, lightweight, resilience, low cost, can have film coatings, e.g. in white or with wood patterning e.g. holes/pegboard, used to make cheap furniture components for commercial and household furniture eg cabinet panels, room dividers, exteriors of television cases, bottoms of drawers etc.
• Polymer laminates


  Melamine formaldehyde laminates give a protective and attractive surface finish to low-cost timbers, laminates can make materials hard and durable that would be soft, melamine formaldehyde is resistant to heat, moisture and chemicals and its wipe-clean surface improves hygiene
• Wood veneers


  Veneers are stuck to the surface and edges of manufactured boards to improve aesthetics, highly-prized hardwoods are often used to make veneers to add value to low-medium cost materials, this allows manufacturers to harness the aesthetic qualities of a hardwood without the cost, marquetry is a traditional method for creating ornate wooden inlays
• Performance characteristics


  • Grain pattern or direction
  • Warpage
  • Shrinkage
  • Splitting
  • Machining qualities
  • Resistance to decay
  • Mixture
  • Toxicity
• Wood grain


  • Affects workability and cost
  • Decorative grain - oak, mahogany and olive wood
  • Beech has tight and fine grain, easy to turn
  • End grain pattern at end of piece of wood
• Wood structure


  • Wood fibres made from hollow straw-like cells(tracheid) which are held lignin
  • Tracheid carries water and nutrients to from roots and leaves
  • Wood string along length
• Going against grain


  • Looking at rays rising to surface of wood
  • Wood split in direction of rays
  • Planing with the grain avoids tearing wood
• Anisotropic


  • Anisotropic material is physical properties that is affected because of different directions e.g wood
  • Natural wood is stronger along grain than across it
  • MDF and plywood no grain not anisotropic
• Surface defects


  • Manufactured boards uniform in shape finish
  • Natural woods are much less predictable
  • Knot tricky to work with and fall out
  • Create marks on timber from mill
  • Woods damaged by insect attack, disease and rot
  • Defect overall stability of wood