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Spiral Grain and Wave Phenomena in Wood Formation
It is widely recognized that spiral grain in trees severely reduces the value of sawn timber through warping and loss of strength, and that it also causes problems for other wood uses as diverse as transmission poles or plywood. Yet, paradoxically, there are highly valued grain patterns including wavy and interlocked grain, whose origins in the cambium invite direct comparison with those of spiral grain, so that many authorities believe them to be related phenomena. In recent years this concept has prompted extensive research into the anatomy, genetics, and physiology of all such grain patterns in wood. As a result it has become apparent that tree cambia provide excellent systems through which to study the origins of stem polarity and the complex processes of morphogenetic control in plants. Beside these and other pressing topics for research, the book examines methods of measuring grain deviations, and considers their influence on wood properties, on the economics of timber production, and on wood manufacturing.
Spiral Grain
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Spiral Grain in Wood
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Spiral Grain
Excerpt from Spiral Grain: A Cause of Pole Twisting The study of cause of twisting of poles soon pinpointed spiral grain as a major cause. In 290 poles in four power transmission lines, left spiral grain occurred about three times as frequently as right spiral, and poles usually twisted in the same direction as their spiral grain. Left-spiraled poles usually twisted more than right-spiraled poles, and all severe twisting was associated with severe spiral grain on the pole's surface. Well -seasoned poles twisted less than unseasoned or briefly seasoned poles. Results of a study aimed at finding a practical method of detecting spiral grain in poles before debarking were disappointing. Neither ...
Spiral Grain
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