WOOD(2)

• SOFTWOODS come from the conifers (evergreens) which have needles instead of leaves, e.g. pine
• HARDWOODS come from the broad-leaved or deciduous trees. Most Philippine timber are of this latter kind
• SAPWOOD is the softer, younger outer portion of a tree that lies between the cambium (formative layer just under the bark) and the heartwood
• SAPWOOD is more permeable, less durable and usually lighter in color than the heartwood
• SAPWOOD it contains more organic matter than the central core of the log, it is more susceptible to blueing fungi and woodboring insects, and is not durable.
• HEARTWOOD The central core of the log, it is composed of inactive cells and serves only as a mechanical support
• DECAY • Caused by the attack of fungi.
• CHECKS • Cracks or lengthwise separation across the annual rings of growth caused by irregular shrinkage during drying. Checks are formed when the circumference shrinks more than the interior section of the log.
• SHAKES • These are cracks between and parallel to the annual rings of the growth.
• KNOTS • These are irregular growths in the body of a tree which interrupt the smooth curve of the grain. The fibers of the tree are turned from their normal course and grow around the knot at that point of the tree.
• PITCHPOCKETS • These are well-defined openings between annual rings containing solid or liquid pitch.
• WANE • This is the lack of wood on the edge or corner of a piece.
• WARPING • Any variation with the plane surface of the piece caused by unequal shrinkage of the board. There are several forms of warp:
• Crook • a distortion of the board in which the edge is convex or concave longitudinal.
• Bow • a distortion of the board in which the face is convex or concave longitudinal.
• Cup • a distortion of the board in which the face is convex or concave across the board.
• Twist • a distortion of the board in which one corner is raised
• Plain Sawing refers to lumber cut tangent to the annual rings or growth or, in commercial practice, cut with annual rings at an angle 0 to 45 degrees and is preferable when a pleasing pattern is required, as in wall paneling.
• QUARTER SAWING • refers to wood cut radially to the annual rings of growth parallel to the rays or, in commercial practice, cut with the annual growth rings at an angle 45 to 90 degrees
• QUARTER SAWING it has less shrinkage than plainsawn lumber, and this is important where joints must be kept tight.
• RIFT SAWING • is a woodworking process that aims to produce lumber that is less vulnerable to distortion than flat sawn lumber.
• Strips. Lumber less than 2” thick and less than 8” wide.
• Board Lumber. Pieces less than 2” thick and at least 8” wide
• Dimension Lumber. Pieces more than 2” and less than 5” in any dimension.
• Timbers. Pieces 5” or more on the smallest dimension
• Nominal size is the size of lumber when it is cut from the log. After cutting, the lumber is dried and then planed on all four sides to achieve smoothness. The finished size is therefore smaller
• When all free water is removed but all absorbed water remains, the so-called “fibersaturation point” (approximately 30% moisture content (M.C.) for all species) is reached.
• This condition of dryness of the wood is called “equilibrium moisture content” (E.M.C.) and in the Philippines this is equivalent to from 12 to 16 percent moisture content.
• The process of removing moisture from green wood (wood from freshly-cut logs) is called seasoning
• KILN-DRYING in which warm moist air or superheated steam is used to heat the wood and drive out moisture.
• Decay- Molds, stains and decay in wood are caused by fungi. Their growth depends on mild temperatures and dampness.
• Subterranean termites which live in the ground and build earthen tubes to reach their food
• Non-Subterranean termites The only relatively permanent method of arresting attack is to use lumber that has been given full-length termite proofing with wood preservatives. Attention to structural features and sanitation are also important.
• CarpenterAnts and Powder-Pest Beetles use wood for shelter rather than for food, but if they are not found and are left undisturbed they can do extensive damage. They convert wood to powder, shredded fibers or pellets. Their channels are likely to cut across the grain. The damage to wood by the various marine organisms, mollusks and crustaceans in salt water or brackish water is best arrested by heavy, thorough treatment with coal-tar creosote or creosote-coal tar solutions.
• Coal-tar creosotes. Black or brownish oil made from distilling coal tar. Advantages are: highly toxicity to wood-destroying organisms; insolubility in water; ease of application. Disadvantages are its strong, unpleasant odor, cannot be painted, easily ignited when first applied .
• Pentachlorophenol a mixture of petroleum oils and 5% and pentachlorophenol. Has high protection against decay fungi and termites; can be painted; has no unpleasant odor; is less easily ignited than coal-tar creosotes. Provide less protection against marine borers
• Chromated Zinc Chloride. Gives protection against decay, insects and fire; can be painted; has no objectionable odor. Disadvantages are: wood cannot be used in contact with the ground or water
• Pressure treatment. Consists in placing the wood in cylinders into which the preservative is pumped under pressure
• Hot and Cold Bath Method. This consists first in placing the wood in a bath of hot preservative for an hour or more. It is then withdrawn and quickly placed in a bath of cold preservative. This is generally used for creosote preservative
• Plywood is the most common wood composite. It gets its name from its construction: it is made of several thin plies, or veneers, of wood that have been glued together. Each ply or veneer is glued so that its grain is at right angles to the grain of the previous ply.