Some occur naturally such as rapid growth, fungal and insect attack, broken limb or other injury. Another category of defects are more innate and caused by the characteristics of wood in regards to the correlation between water vapor in the air and the shrinking or expansion of the wood. Furthermore, certain defects are more artificial and can

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stages of Seasoning/drying. A defect is simply an abnormality or irregularity found in wood. There are many different types of defects arising from many different causes. For instance, there are natural and acquired defect s caused by a broken limb or other injury, insect and fungal attack, or rapid tree growth. There are innate defects caused

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Feb 19, 2016 Caused by rapid drying out on the surface of the wood. Honeycomb splits/checks Occur inside the board. Reduces strength. Case hardening Where the outside of the board is dry and hard but moisture is trapped in the centre cells of the wood. Caused by rapid drying. CONVERSION DEFECTS

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The important point is that ring shake is a wood quality condition not a drying defect. The split or crack did not originate in the dry kiln or the drying process. Instead, it originated in the standing tree. It is also important to note that shake may not be easily detected in green logs and lumber. It may only become apparent after drying

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Aug 21, 2020 A defect is an irregularity or abnormality occurring inside or on the surface of the Wood or Timber which can affect its strength, appearance, durability and other properties. Defects may be due to poor natural growth of the Wood, wood diseases, rapid seasoning and faulty processing. Here we are going to discuss various types of defects in timber

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Aug 15, 2019 The defect is due to the corrugates appearance of timber , caused due to excessive and uneven shrinkage during drying. 4)Foxiness : This defect is due to yellowish or reddish stains , caused by over-maturity and lack of ventilation during storage of timber

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Feb 23, 2020 There are innate defects caused by the natural characteristic of wood to shrink or expand in response to water vapor in the air. And, there are artificial and mechanical defects caused by incorrect sawing or machining (conversion), improper drying

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Hence the dry wood having moisture content less than 20% will remain sound for centuries. Similarly the wood submerged in water will not be attacked by fungi because of absence of air. Following defects are caused in the timber by the fungi: ... The most favourable conditions for the rapid growth of fungus responsible for dry rot are absence of

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Oct 25, 2021 7. Shake is a lengthwise crack or separation of the wood between the growth rings, which often extends along the face of the board and sometimes below its surface. Shakes can partially or completely separate wood fibers. When appearance is important, the separations make the wood unappealing. Although this is a naturally occurring defect caused by frost or wind stress, shakes can

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Natural / Felling Defects Types of Shakes 1. Heart and Star shakes Deep, wide cracks which radiate out from the centre of the log Caused by shrinkage through old age or by too rapid drying after felling Cracks or splits in the wood are called shakes Types of Shakes Cup and ring shakes Gaps between growth rings, that can be very deep, are known as cup or ring shakes

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Sep 02, 2013 Defects Due to Seasoning • Case Hardening- it is due to the unequal drying of the exterior surfaces under compression and the interior surfaces under tension due to rapid drying. • Split- separation of the fibers along the grain and extends from one end of the plank to the other

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of fibre caused by the tearing apart of wood parallel to the wood rays) and pre-drying was recommended for this species before kiln drying, in addition to a slow-drying schedule (Piao et al. 2000). Acacia mangium lumber obtained from thinning and clear cuts of fast-growing plantations developed severe drying defects (Basri & Wahyudi 2007)

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pected defects appear in dried wood products, their cause is often blamed on the drying operation. The purpose of this chapter is to describe the various types of defects that can occur in dried wood products and to show how these defects are related to the kiln-drying operation. Many features of wood affect its utility when it is pro

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It is a wood defect that is caused by rapid drying What are wood defects. curvature that forms in the direction of the length of the wood. The blue stain, the sap stain and the brown brown are the defects caused in wood by mushrooms. 2. Dry rot is a defect caused in wood where the wood is converted into dry powder form by mushrooms

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A bow is a defect in a board that bends along the grain lines. If the board were laid across a flat surface, both ends would be in the air. There is no warp across the grain. This can be caused by uneven air circulation as the wood dries. Any bowing causes internal

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Apr 04, 2016 A defect is simply an abnormality or irregularity found in wood. There are many different types of defects arising from many different causes. For instance, there are natural and acquired defects

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Jun 26, 2017 A longitudinal crack that does not go through the whole log or plank; usually caused by too-rapid seasoning. Chipped grain. Torn grain due to poor machining or finishing. Collapse. A caved-in cell structure, caused during drying, giving a shrivelled or

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Apr 03, 2012 Rapid Drying. Can effect the strength and appearance of the board. Should be cut off or worked around. Crook: Warping along the edge from one end to the other. This is most common in wood that was cut from the center of the tree near the pith. Can be caused by improper drying and storage or the presence of reaction wood. Can be difficult to

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wood surface is covered with small splits along the grain caused by too rapid drying in hot sun. flaking the surface of the wood lifts in innumerable small flakes or layers which spring under the cutting action, preventing a smooth surface

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Aug 15, 2019 The defect is due to the corrugates appearance of timber , caused due to excessive and uneven shrinkage during drying. 4)Foxiness : This defect is due to yellowish or reddish stains , caused by over-maturity and lack of ventilation during storage of timber

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The stage in the drying or wetting of wood at which the cell walls are fully saturated but the cell cavities are void of water, ranging from a moisture content of 25% to 32 % for commonly used species. Further drying results in shrinkage and generally greater strength, stiffness, and density of the wood

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