Wood-120-2018W-Lec-3-Grading-RF.pdf

Cuttings one sound completely intergrown red knot

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Cuttings: One sound, completely intergrown red knot with a minimum of one for each lineal feet of length One sound, tight black knot up to ¼ in diameter in cuttings 6 lineal feet in length Not permitted: Black knots, pith, checks, shake, splits, warp, wane, pitch pockets, worm holes, rot, stain Back: Sound, allowing no rot, shake, wane, unsound knots, or defects that seriously weaken the cutting
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Species Covered – NLGA Grading Rules Western Red Cedar Yellow Cedar Douglas Fir Western Hemlock Western Larch Lodgepole Pine Black Spruce Balsam etc. Figure 1: Examples of different species – Picture captured by R. Fuerst
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Natural Growth Characteristics Characteristics can be divided into three broad groups: 1) Natural: Caused by nature: that is, characteristics which occur or develop on the living tree 2) Manufacturing: Those caused by equipment during manufacturing and handling 3) Seasoning: Those caused by drying
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1) Types of Natural Defects Rate of growth Irregular growth Direction of growth Discoloration Knots Catfaces Holes Bark or pitch pockets Mineral streaks Shakes Burls Stained wood White specks Honeycomb, Peck Unsound wood Compression wood
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Examples - Knots Sound Knots (intergrown knot) Knot grown firmly into the surrounding. Does not contain any bark or signs of decay. Encased Knots A knot surrounded with pitch or bark Spike Knot Is produced when the limb is cut either lengthwise Figure 2: Examples of different knots – Picture captured by R. Fuerst
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Example - Wane Wane usually occurs on the edge of the piece where the bark has come off or a piece has been chipped out. Figure 3: Examples Wane – Picture captured by R. Fuerst
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Pitch Pockets - Shake Pitch Streak/Pockets develop during the growth of the tree and usually contain liquid or granulated pitch Shake – separation of the wood between the growth rings. (develops in the standing tree) Figure 3/4: Examples Pitch Streak and Shake – Picture captured by R. Fuerst
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Example - Compression Wood Wood that forms on the underside of a leaning coniferous trees Can be identified by the colour of the grain Compression Wood Tension Wood Figure 4/5: Examples Tension Wood and Compression
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2) Manufacturing Defects Picaroon holes Dog holes Tolerances in sawing Scantness in thickness Roughness in dressing Hit or Miss
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  • Fall '14
  • SimonEllis
  • Robert Fuerst,  NLGA

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