Wood warping is a deviation from flatness in

timber Lumber is wood that has been processed into dimensional lumber, including beams and planks or boards, a stage in the process of wood production. Lumber is mainly used for construction framing, as well as finishing (floors, wall panels, wi ...

as a result of stresses and uneven shrinkage. Warping can also occur in wood considered "dry" (wood can take up and release

moisture Moisture is the presence of a liquid, especially water, often in trace amounts. Small amounts of water may be found, for example, in the air (humidity), in foods, and in some commercial products. Moisture also refers to the amount of water vapo ...

indefinitely), when it takes up moisture unevenly, or – especially – is allowed to return to its "dry" equilibrium state unevenly, too slowly, or too quickly. Many factors can contribute to wood warp: wood species,

grain A grain is a small, hard, dry fruit (caryopsis) – with or without an attached hull layer – harvested for human or animal consumption. A grain crop is a grain-producing plant. The two main types of commercial grain crops are cereals and legum ...

orientation, air flow, sunlight, uneven finishing, temperature – even cutting season and the moon's gravitational pull are taken into account in some traditions (e.g.,

violin making Making an instrument of the violin family, also called lutherie, may be done in different ways, many of which have changed very little in nearly 500 years since the first violins were made. Some violins, called "bench-made" instruments, are made ...

). The types of wood warping include: * bow: a warp along the length of the face of the wood * crook: a warp along the length of the edge of the wood * kink: a localized crook, often due to a

knot A knot is an intentional complication in cordage which may be practical or decorative, or both. Practical knots are classified by function, including hitches, bends, loop knots, and splices: a ''hitch'' fastens a rope to another object; a ' ...

* cup: a warp across the width of the face, in which the edges are higher or lower than the center of the wood * twist or wind: a distortion in which the two ends do not lie on the same plane.

Winding stick An electromagnetic coil is an electrical conductor such as a wire in the shape of a coil (spiral or helix). Electromagnetic coils are used in electrical engineering, in applications where electric currents interact with magnetic fields, in de ...

s assist in viewing this defect. Wood warping costs the

wood industry The wood industry or timber industry (sometimes lumber industry -- when referring mainly to sawed boards) is the industry concerned with forestry, logging, timber trade, and the production of primary forest products and wood products (e.g. furnit ...

in the

U.S. The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...

millions of dollars per year. Straight wood boards that leave a cutting facility sometimes arrive at the store yard warped. Although wood warping has been studied for years, the warping control model for manufacturing

composite wood Engineered wood, also called mass timber, composite wood, man-made wood, or manufactured board, includes a range of derivative wood products which are manufactured by binding or fixing the strands, particles, fibres, or veneers or boards of woo ...

hasn't been updated for about 40 years. Zhiyong Cai, researcher at

Texas A&M University Texas A&M University (Texas A&M, A&M, or TAMU) is a public, land-grant, research university in College Station, Texas. It was founded in 1876 and became the flagship institution of the Texas A&M University System in 1948. As of late 2021, T ...

, has researched wood warping and was working on a computer software program in 2003 to help manufacturers make changes in the manufacturing process so that wood doesn't arrive at its destination warped after it leaves the mill or factory.

References

*WoodWeb �
Warp in Drying
*Society of American Foresters �
Warped Wood
{{Woodworking Woodworking Timber industry Deformation (mechanics)

See also

References