What is a Grain
This term refers to the lines found in natural wood, which are a result of the growth rings of the tree from which the wood is taken. Though those rings serve as yearly markers of the tree's growth, their thickness varies from specimen to specimen as no two trees experience the exact same conditions. The orientation of the grain, meanwhile, is mainly determined by how the tree was cut during processing.
During processing, many logs are cut through quarter-sawing, which cuts the wood into parallel planes. A technique referred to as rift sawing, however, may occasionally be used instead. In rift sawing, a log is halved before boards are cut from it at radial angles. This technique is usually only used to achieve a specific style of grain, as it possesses a much greater potential to waste wood than quarter-sawing. Rift sawing, however, does have an advantage in that the cut is done precisely perpendicular to the growth rings of the tree. The boards created through this technique are, in turn, typically more stable than those produced through quarter-sawing and boast straighter grain lines. Flat sawing is more commonly used than either of those methods due to its efficiency and low level of waste; the resulting grain patterns, however, are generally not as appealing as those resulting from the other two techniques.