Waviness

A surface property of a gravure cylinder that describes the large-scale uniformity of the copper or chrome plating. The plating and polishing of the copper surface of the gravure cylinder yield a certain degree of large peaks and valleys which need to be minimized as much as possible. A high degree of waviness on the surface of the copper plating results in ink transfer in non-image areas, due to incomplete ink removal by the doctor blade. Although the gravure cylinder's copper surface is covered with a layer of chrome after engraving, the combination of the thinness of the chrome layer and the physical principle of epitaxy (or the tendency for the electroplated chrome to follow the contours of the copper to which it is plated exactly) allow for no correction or smoothing out of irregularities in the copper surface.

Copper and chrome waviness is measured by moving a diamond across the surface and measuring the peaks and valleys. A related property is roughness, which is similar to waviness but on a smaller scale. (See also Roughness.)

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