Wood Technology

Structure and Growth  Formed of long tubular fibers, about 1/25in in length in hardwoods and 1/8in for softwoods  Annual rings- composed of springwood and summerwood Depends on type of wood Growing conditions

Structure and Growth  Sapwood- thick living cells  Heartwood- inactive sapwood  Cambium- layer inside the bark where the water travels

Structure and Growth  Softwood cell structure Tracheids- transport sap and strengthen wood Thin rectangular cell units  Hardwood cell structure Vessels- conducting sap vertically Porous wood with large holes or pores

Moisture Content  Trees can be up to 75% water  Fiber Saturation Point- cells wall are full of water while cell capsule is empty  % Moisture Content= Initial Wt. – Oven-dry Wt x 100 Oven-dry Wt

Drying Methods  Air Drying- 30 to 60 days during active drying weather, up to 6 months during unfavorable weather  Oven drying- 1in board can be dried 6 to 10% MC in 3 to 4 days Increases heat while decreasing humidity

Drying Methods  Radio-frequency drying- drying time approximately 24 hours Hardwood dry best with this method Improves color and quality Causes uniform drying

Equilibrium Moisture Content  Moisture content in the wood is equal or close to the moisture content in the air  Slight changes cause door and windows to stick during humid weather

Lumbering  Bucking- limbs are removed and log is cut into specific lengths  Logs can be stored in water to prevent insect damage and splitting

Plywood and Veneer  Rotary- follows the growth rings when being cut Veneer is very wide  Plain slicing- parallel slices through log Produces a variegated figure  Quarter slicing- parallel slices in a quarter portion of a log Causes striped wood look

Manufactured Board  Hardboard- (Masonry Board) formed by bonding wood fibers together  Particle Board- bonding wood flakes and chips together

Manufactured Board  Wafer Board- wafers randomly formed together  Oriented strand board-formed from long strands of wood parallel to one another