Wood Products Classification of Timber

Mineral Fiberboard

• Made from asbestos fibers mixed with cementing agent
• Ideal for fireproofing and acoustical purposes

Wood and Wood Products

• Chipboard: made from building board particles and a binder (phenolic resin/urea formaldehyde glue)
• Often faced with veneer
• Lends itself to a range of stain and paint finishes for indoor use
• Weather-resistant, making it valuable for outdoor installation
• Can be laminated for plywood as interior finishing
• Used for sub-flooring, interior and exterior walls

Sub-types of Chipboard

• Plain: unsanded, sanded on one side, or sanded on two sides
• Patterned: one grooved surface, either evenly or randomly

Particle Board

• Made from hardboard from relatively small particles, graduated from coarse at the center of the board to fine at the surface
• Produces a smooth, dense surface
• Both sides or one side of the surface are sanded, while edges are filled according to particular uses
• Can serve as a base applied with wood veneers, plastic laminates, printed wood grains, and chalkboard coating
• Used for shelving, millwork, and other furniture manufacturing

Gypsum Board

• A wall board having a gypsum core
• Variations:
  • Special paper face where wood patterns can be printed and can be nailed with colored nails
  • Glue-laminated to an interior surface to produce a wood grain effect
  • Vinyl sheet-faced, made to imitate a textile surface, held by glue or aluminum or plastic moldings

Classification of Timber

• Based on seasoning characteristics:
  • High refractory (Class A): slow and difficult to season, free from defects
  • Moderate refractory (Class B): may be seasoned free from surface defects with some protection
  • Non-refractory (Class C): can be rapidly seasoned free from defects
• Based on treatability:
  • Easily treatable
  • Treatable but complete preservation not easily obtained
  • Only partially treatable
  • Refractory to treatment
  • Very refractory to treatment, with penetration of preservative being practically nil from the sides and ends

Structure of Timber

• A tree can be divided into three portions: crown, trunk, and roots
• The trunk accounts for about 80% of the total bulk of wood

Characteristics of Good Timber

• Principal characteristics of concern: strength, durability, and finished appearance
• Narrow annual rings, the closer the rings, the greater the strength
• Compact medullary rays
• Dark color
• Uniform texture

Wood Products

• Many wood-based products have been developed to economize on the use of timber
• Manufactured under controlled conditions in factories
• Desired shape, dimensions, appearance, strength, and durability

Types of Wood Products

• Veneers: thin sheets of wood, 0.4 to 0.6 mm in thickness, not exceeding 1 mm
• Plywood: a wood panel glued under pressure from an odd number of layers of veneers
• Fiber Boards: manufactured in various densities, soft, medium, and hard
• Building Boards: a group of sheets of building materials, often faced with paper or vinyl, suitable for use as a finished surface

Properties of Boards/Wood

• Strong across and along the panel, with more plies meaning near equal strength in both directions
• Shrinking and swelling can be neutralized due to wood grains running in one direction
• Splitting in its plane is impossible due to successive layers at right angles to each other
• Plywood can be bent more easily than ordinary wood of the same thickness
• Curvature depends on thickness and is limited by the strength of the outer pile in tension and inner piles in compression
• Plywood offers numerous possibilities for decoration due to the great variety of colors and textures
• Decorative effects can be achieved on the face ply by pressure, sandblasting, or etching with wire brushes