hygroexpansivity
A change in the dimensions of a material, such as
paper, because of a change in the ambient relative
humidity of the atmosphere surrounding the
material. The phenomenon is usually expressed as a
percentage, and is generally several times greater
in the cross direction of a paper than in the MACHINE DIRECTION ,
because paper fibers expand much more in diameter
than in length when wetted. Hygroexpansivity is of
considerable importance where the dimension of
paper is critical, such as in multi-color offset
printing. See also: ANISOTROPIC BEHAVIOR
;DRIED-IN STRAIN .
(17 , 72 )
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