page_title: Wood grain
section_title: Physical aspects
hierarchical_section_title: Wood grain / Physical aspects
caption_attribution_description: English: Image taken from US Department of Agriculture, Forest Products Laboratory, The Wood Handbook: Wood as an engineering material, page 3-2, by cutting and pasting using Adobe Acrobat Reader and converting to PNG using Irfanview.
context_page_description: Wood grain is the longitudinal arrangement of wood fibers or the pattern resulting from this.
context_section_description: Perhaps the most important physical aspect of wood grain in woodworking is the grain direction or slope (e.g. against the grain). The two basic categories of grain are straight and cross grain. Straight grain runs parallel to the longitudinal axis of the piece. Cross grain deviates from the longitudinal axis in two ways: spiral grain or diagonal grain. The amount of deviation is called the slope of the grain.
  In describing the application of a woodworking technique to a given piece of wood, the direction of the technique may be:
  with the grain (easy; giving a clean result)
  against the grain (heavy going; giving a poor result such as chipping or tear-out)
  across the grain (direction of cut is across the grain lines, but the plane of the cut is still aligned with them)
  end grain (at right angles to the grain, for example trimming the end of a plank)
  Grain alignment must be considered when joining pieces of wood, or designing wooden structures. For example, a stressed span is less likely to fail if tension is applied along the grain, rather than across the grain. Grain direction will also affect the type of warping seen in the finished item.
  In describing the alignment of the wood in the tree a distinction may be made. Different tree species may have one of the following basic grain descriptions and types: 
  straight - grain which runs in a single direction, parallel to the axis of the tree. Woods with this grains are the easiest to work.
  spiral - grain which spirals around the axis of the tree.
  interlocked - grain which spirals around the axis of the tree, but reverses its direction for periods of years resulting in alternating directions of the spiral grain. On quartersawn surfaces the change in grain direction creates a ribbon stripe figure. These are the most difficult to work.
  wavy - grain which grows in a wavy fashion up the trunk; seen best in flatsawn sections of wood.
  irregular - grain that swirls or twists. It can be found in a number of different patterns. This can be caused by factors such as knots, burls or "crotch" wood - where large branches separate from the trunk.
caption: Sketch of A—Quarter-sawn & B—flat-sawn
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