Wood is a natural material that has large variations in grain structure, mostly due to the presence of knots and spiral grain
. The resulting variations in wood grain (fiber) direction strongly affect the strength of the wood; even a small deviation in grain direction significantly weakens the lumber.
Examination of the photo of the tusk taken at the time of capture shows that a concentric spiral grain
at that position of the tusk was about 15 cm long (~ length of the steel portion of the transmitter) for a 180[degrees] rotation.
Two of the trees have straight trunks, but the other has a somewhat spiral growth form that is associated with a spiral grain
in the wood.
Results demonstrated that spiral grain
substantially reduced the strength of utility pole wood.
During the final period of drying, several visual characteristics of the poles were measured and recorded, including spiral grain
, ovality, taper, rate of growth, sweep, fissures, and knots.
Tamarack wood frequently contains spiral grain
. To avoid warping during the drying process, the kiln operator must take special precautions, such as the application of top-load restraint and the use of a high-temperature schedule to take advantage of the plasticization effect of heat on wood.
Interlocked grain (also called double spiral grain
) is a characteristic feature of a great number of tropical species and a few domestic hardwoods such as tupelo, blackgum, sweetgum, sycamore, cottonwood, and elm (Davis 1962, Webb 1969, Chudnoff 1984).
To assess the geospatial and within-tree variation in wood density and spiral grain
in Douglas-fir stems, over 400 wood disks were collected from 17 sites in the Cascade and Coastal Ranges of Oregon.
1995); 2) spiral grain
angle--the higher the spiral grain
angle, the larger the twist (Balodis 1972, Mishiro and Booker 1988, Johansson et al.
The Master grade refers to a tonewood board containing more than 95 percent quartersawn material, no defects, no spiral grain
, even grain lines, white color, good stiffness, no compression wood, and no dark growth lines.
Among them, slope of grain (SOG), defined as the angle between the direction of the wood grain and the main axis of a lumber piece that could either be a consequence of the sawing process or a natural occurrence in trees or logs (spiral grain
), can cause shape deformations.
It is speculated that since spiral grain
is a leading cause of twist in lumber, trees with high sweep may have a lesser amount of spiral grain