Surface of printed paper was studied by using a non-contact type surface roughness meter. A black offset ink was transfered on a cast- coated paper, which is the plainest paper traded. In a sample transfered small amount of the ink (
y=ca. 0.1gm
-2), ink grains were attached on the tops of unevenness of the paper. Roughness for a center line of the surface (
Ra), therefore, is increased from 0.69μm (paper) to 0.82μm, the maximum value. The
Ra value was decreased with increasing the amount of the transfered ink to
Ra=0.32μm at the sample with 0.8gm
-2 of the ink. This amount of the ink seems to be suitable amount to cover on the paper without deep holes distributed on the paper surface. Over y=1.8gm
-2, the uncovered areas could not be obserbed. The minimum
Ra(=0.29μm) value was obtained in the sample with y=3.9gm
-2. Glossy (
Gs) of the surface was also measured by the use of a goniometer. Because
Gs is in invers proportion to
Ra,
Gs is closely related with the roughness of the printed surface.
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