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Wood Technology

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

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Wood Technology

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  1. Wood Technology

  2. 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

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

  4. 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

  5. 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

  6. 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

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

  8. 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

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

  10. 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

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

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

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