Definition
Wood that has been sawn so the annual growth rings meet the wide face of the board at an angle of 45 degrees or more, ideally close to 90 degrees. Also called vertical-grain or quarter-sawn wood, it is preferred for aircraft structural use because it is dimensionally stable and resists warping, splitting, and shrinkage better than flat-grain wood.
Plain English
A piece of wood cut so the growth rings run nearly straight up and down across the narrow edge of the board. This kind of cut produces a strong, stable plank that holds its shape well over time.
Context Anchor
Seen in aircraft wood construction, inspection, and repair when choosing or approving wood for structural parts.
Derivation
Called 'edge-grain' because when you look at the end of the board, the grain lines (the growth rings) appear to run straight across the edge rather than across the flat face. The term describes what you actually see when you stand the board on edge and look at the cut.
Why Pilots Care
Edge-grain wood offers greater strength, stability, and resistance to splitting, which is essential for parts that must withstand flight loads and vibration.
Intuition Check
Do not read “edge-grain” as simply meaning grain near the edge of a board. It means the growth rings are oriented mostly upright relative to the board’s wide face.
Example Sentence 1
The repair manual specified edge-grain spruce for the wing spar replacement, so the mechanic rejected the flat-grain stock on the bench.
Example Sentence 2
Inspectors rejected the spar stock because the grain ran flat rather than edge-grain.