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