In Graphic art reproduction process it is important to realize that which set of inks and their densities ( film thickness ) and which set of halftone positive should be aimed at in order to meet the demand for good color reproduction. These have been various studies ti calculation the color reproduction of the graphic arts, however , these study were based on the assumed characteristics of the materials. In this study the relationship between wet - trapping ( wet on wet- printing) and increases of ink layer and printing sequence are examined