wood technology. structure and growth formed of long tubular fibers, about 1/25in in length in...
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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