2.4 Optical density Yang, Gao & Jiang (2012) investigated Study on the Relationships between the Optical Density and Ink Film Thickness Based on the Offset Overprint Trapping. D=D∞ (1-e-ml) formula represents the relationship between ink thickness and ink density. By using the formal of one-color ink thickness and ink density, the second density that corresponds the first major density is transferred to the equal thickness. Then they are added together. The experiment was carried out using 128 & 157 GSM art matt paper, 60 & 100 GSM offset paper; and Offset glossy and quick-drying ink of TGS brand. Papers were printed with different color and 10 different volume inks. Primary colors were overprinted in sequence CY; MY and CM. Then various primary
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Paper surface efficiency formula which integrates gloss, ink absorbency and whiteness was first presented and it was assumed that change of these principle paper properties would affect color reproduction. This experiment was conducted with the help of papers: Chenming double-sided gloss coated papers with 250 g/m2, 200 g/m2, Chenming double-sided matt coated papers with 128 g/m2 and 105 g/m2, Dongfan double-sided gloss coated papers 128 g/m2, Daewoo double-sided coated paper 157 g/m2, Huaxia double-sided coated paper 128 g/m2, Yatai lightweight coated paper with 80 g/m2 and 60 g/m2 ; and magenta and cyan ink of sheet-fed offset printing. The WSB-Ⅱdigital whiteness meter, the NOVO-Gloss gloss meter, the YM-20 K&N ink absorbency tester, the C1-5IGT printability tester and the 528 spectrophotometer were used as instruments. Paper samples were treated at 22-230 C, 50-55% relative humidity for 24 hours. Then whiteness, gloss and ink absorbency were tested. These paper samples were printed with magenta and cyan ink with same ink density as that of ink printed on different paper samples. Results were compared after 24 hours to obtain a …show more content…
When the ink layer on paper is too thin, it is caused by less printing pressure and less amount of ink is transferred. The central position of plate cylinder is moved to change the pressure between the plate cylinder and the blanket cylinder. Center distance between the plate cylinder and the blanket cylinder is controlled by gear system driving each other. Screen tone graphics are distorted when the printing pressure is too big. To achieve the optimum amount of screen tone and adequate amount of ink transfer, ideal pressure should be determined. If the printing pressure is too much or too less center distance between the plate cylinder and the blanket cylinder is regulated. Machine component dimensions are changed depending upon distance required between the plate cylinder and blanket cylinder and amount pressure required. By changing dimensions of components, rubber deformation is increased or decreased, changing the transfer rate of ink. Quality problems such as color out of tune, distortion of picture and text and layer fuzziness could be avoided by implementing the technique. By means of the vector relationship of pressure regulation, the rotation angle of eccentric bearing on the plate cylinder and length change of regulating screw were worked out. A certain basis for printing pressure and printing quality was set by analyzing the effect of the pressure regulating device on printing
Paper surface efficiency formula which integrates gloss, ink absorbency and whiteness was first presented and it was assumed that change of these principle paper properties would affect color reproduction. This experiment was conducted with the help of papers: Chenming double-sided gloss coated papers with 250 g/m2, 200 g/m2, Chenming double-sided matt coated papers with 128 g/m2 and 105 g/m2, Dongfan double-sided gloss coated papers 128 g/m2, Daewoo double-sided coated paper 157 g/m2, Huaxia double-sided coated paper 128 g/m2, Yatai lightweight coated paper with 80 g/m2 and 60 g/m2 ; and magenta and cyan ink of sheet-fed offset printing. The WSB-Ⅱdigital whiteness meter, the NOVO-Gloss gloss meter, the YM-20 K&N ink absorbency tester, the C1-5IGT printability tester and the 528 spectrophotometer were used as instruments. Paper samples were treated at 22-230 C, 50-55% relative humidity for 24 hours. Then whiteness, gloss and ink absorbency were tested. These paper samples were printed with magenta and cyan ink with same ink density as that of ink printed on different paper samples. Results were compared after 24 hours to obtain a …show more content…
When the ink layer on paper is too thin, it is caused by less printing pressure and less amount of ink is transferred. The central position of plate cylinder is moved to change the pressure between the plate cylinder and the blanket cylinder. Center distance between the plate cylinder and the blanket cylinder is controlled by gear system driving each other. Screen tone graphics are distorted when the printing pressure is too big. To achieve the optimum amount of screen tone and adequate amount of ink transfer, ideal pressure should be determined. If the printing pressure is too much or too less center distance between the plate cylinder and the blanket cylinder is regulated. Machine component dimensions are changed depending upon distance required between the plate cylinder and blanket cylinder and amount pressure required. By changing dimensions of components, rubber deformation is increased or decreased, changing the transfer rate of ink. Quality problems such as color out of tune, distortion of picture and text and layer fuzziness could be avoided by implementing the technique. By means of the vector relationship of pressure regulation, the rotation angle of eccentric bearing on the plate cylinder and length change of regulating screw were worked out. A certain basis for printing pressure and printing quality was set by analyzing the effect of the pressure regulating device on printing