- A darkening of the wood due to overheating by the machine knives or rolls when pieces are stopped in a machine.
- Includes all defects or blemishes that are produced in manufacturing, such as chipped grain, loosened grain, raised grain, torn grain, skips in dressing, hit and miss (series of surfaced areas with skips between them), variation in sawing, miscut lumber, machine burn, machine gouge, mismatching, and insufficient tongue-and-groove.
- Lumber that has been worked with a tongue on one edge of each piece and a groove on the opposite edge to provide a close tongue-and-groove joint by fitting two pieces together; when end-matched, the tongue and groove are worked in the ends also.
- Wood with 4 to 6 rings per inch.
- A structure in a tree that stores and delivers food horizontally through the trunk. In some species, such as oak, the medullary rays can be quite large. When the tree is quartersawn, the rays become visible on the face of the board. This feature is also known as “ray flecks.”
- Small parallel ripples or ridges produced on the surfaces or edges of wood by cutting tools. In the case of saws, virtually all saw blades or chainsaws produce mill marks.
- Lumber that is in varying widths and grades.
- Generally wood remanufactured in millwork plants; it includes such items as inside and outside doors, windows and door frames, blinds, porch-work, mantels, panel work, stairways, mouldings, and interior trim; it does not include flooring, ceiling, or siding.
- An olive to greenish-black or brown discoloration of undetermined cause in hardwoods.
- Lumber may be both vertical and flat grain.
- Wood processed by chemical treatment, compression, or other means (with or without heat) to impart properties quite different from those of the original wood.
Modulus Of Rupture (MOR)
- A measure of the breaking strength of the wood. The higher the MOR, the greater the force required to break it.
Very Weak: Very easily broken.
Weak: Somewhat easy to break.
Strong: Somewhat difficult to break.
Very Strong: Extremely difficult to break.
Modulus Of Elasticity (MOE)
- A measure of how stiff the wood is. This measures how much force is required to bend a small, clear, straight-grained specimen at a span ratio of 14/1 according to American Society of Testing Material standard D 255-70.
Very Pliant: Very easily bent.
Pliant: Somewhat easy to bend.
Stiff: Somewhat difficult to bend.
Very Stiff: Extremely difficult to bend.
- The moisture content of wood is the weight of the water in wood expressed as a percentage of the weight of the wood from which all water has been removed (oven dry). Moisture is removed from lumber either by air drying or by use of special drying kilns.
The Wood Glossary