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in drying rate and sensitivity to drying defects impose limitations on the development of standard drying pro-cedures. The interactions of wood, water, heat, and stress during drying are complex. The purpose of this chapter is to describe some of the fundamental prop-erties of wood that are relevant to lumber drying. We
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Jun 30, 2013 Mechanical properties of many wood products are assessed by treating them as distributed parameter systems, i.e. as beams, panels and the like. Internal defects detected in specimens, such as decay, knags, cracks and etc., determine the extensive distribution of measured parameters. It becomes especially relevant to evaluate the quality of dried wood assortments, since
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Properly drying the wood before it is installed will also help. Using protective stains on your deck can prevent some damage to the wood by slowing down the drying process in order to limit checking. Stains can also conceal visual defects by covering them with a consistent color throughout the deck
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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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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 (seasoning), or improper handling and storage
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May 13, 2010 Kiln drying of grade hardwood lumber is carried out in a closed chamber or building in which heated, humidity-controlled air is rapidly circulated over
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Sep 07, 2021 Natural defects occur during tree growth, with development of said defects not being able to be controlled by man. Natural defects include knots, shakes, Spalting, etc. Artificial defects are defects that are developed after the lumber has been harvested. These defects arise in various harvesting practices including drying and storage of the
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Because wood is not homogeneous, it shrinks more along the growth rings than across the rings. The least shrinkage or swelling of wood is found in the longitudinal or “tree trunk” direction. These shrinkage variations cause drying defects like warping and checking. Shrinkage and swelling cease as the MC of wood approaches an equilibrium
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be blamed on poor drying practices. A drying defect is any characteristic or blemish in a wood product that occurs during the drying process and reduces the prod-uct’s intended value. Drying degrade is a more specific term that implies a drying defect that lowers the grade of lumber. Every year, drying degrade and other dry
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Honeycomb is an internal crack caused by a tensile failure across the grain of the wood and usually oc- curs in the wood rays (fig. 8-6). This defect develops because of the internal tension stresses that develop in the core of boards during drying (ch. 1)
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Sep 30, 2018 Drying defects in the wood drying equipment processI. Collapse: The so-called collapse mainly refers to the abnormal deformation of the wood due to the extreme deformation of the cell. It is due to the tension and compressive stress caused by the change of water in the cell cavity
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Oct 13, 2018 There are two kinds of discoloration: one is discoloration due to the reproduction of discoloring bacteria and decaying bacteria; and the other is discoloration caused by acidification of components contained in wood in a hot and humid state. Drying wood with high moisture content at high temperatures tends to darken or darken the wood; sometimes the surface of the wood becomes dark
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Decay is caused by microscopic organisms like mold and fungus that feed off the natural substances found in wood. Fungi require four conditions in order to survive: an oxygen supply, 40-100 F temperatures, a supply of moisture (most fungi need a moisture content of 30% or
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