In addition to the actual color and appearance of the wood, there are also more subtle and/or tactile properties of the wood.

Grain Direction: A tree species can grow in a number of grain directions. Grain direction usually can’t be detected from endgrain examination; it may have an effect on the workability or appearance of the wood.

  • Straight: As the name suggests, this denotes species which grow straight and parallel with the tree’s trunk. Straight-grained woods are generally easiest to work and machine with minimal complications.
  • Spiral: Some tree species grow with the grain at a slight incline, with a spiral-like pattern circling the trunk.
  • Interlocked: Taking spiral grain a step further, interlocked grain occurs when spiral-grained trees change directions, and spiral back and forth throughout the trunk, alternating between right-hand and left-hand spirals. Depending on the slant of the spiral, and the frequency of the direction changes, woods can be either shallowly or strongly interlocked. This change in grain direction can be seen the clearest on quartersawn surfaces, which creates a ribbon stripe figure. Both spiral and interlocked grain can present challenges when machining, and may result in tearout.

    This sample of Narra (Pterocarpus indicus) shows a clear ribbon stripe figure, which is formed by interlocking grain spiraling in different directions throughout the tree’s trunk.

  • Wavy: Just as the name implies, this grain pattern indicates when the grain of the wood grows in a wavy fashion. This pattern is most clearly seen in flatsawn sections of wood.
  • Irregular: This is a more ambiguous catch-all term that describes wood grain that swirls or twists in an abnormal way. Irregular grain can be due to a number of factors, such as knots, burls, large branches  separating from the trunk (called “crotch” wood).