The solid density seems to be related to the quality of printing products. Optical prop erties of the solid-prints were analyzed with various densitometer. The solid density depended on areas ratio converted by the ink in the solid prints (coverage ratio) and average thick ness and surface structure of the ink layer on the paper. The effects by surface structure were analyzed with measuring the polarizing solid density and occured in the high density region. The effects by coverage ratio

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... d with dot-area meter occured in the low density region. The effects by average thickness occured in the middle density region.