Comparative Analysis Of Solid Ink Density Of Petroleum And Vegetable Oil (Soya) Inks On Coated And Uncoated Paper Stocks

Abstract

Solid ink density (SID) has continued to be a basic parameter used to evaluate the print quality of the offset process. This paper gives a comparative evaluation of SID among Petroleum oil-based inks and Vegetable Oil (soya) based inks on various paper stocks. A series of printing trials were performed systematically on two substrate types i.e. coated paper and uncoated paper using a standardized CMYK test chart which facilitates uniformity in the experiment. The testing was done on fifty printed sheets in standard condition to minimize variability and set in the statistical reliability of the measurement. The results demonstrate that the Petroleum based inks always achieved slightly higher SID values in all the process colours (C,M,Y, K)as compared to the Vegetable Oil (Soya) inks. When applied on coated surfaces the differences between the two ink systems were not very drastic as penetration of the ink was restricted and thus the results of both ink systems yielded acceptable density. But on uncoated substrates where the density was highly affected by the ink absorbency, petroleum inks had a distinct advantage in Cyan and Magenta channels. The findings suggest that petroleum inks have an advantage when it comes to bigger colour saturation and deeper tonal reproduction. However; inks made of vegetable oil (Soya) base provided the average density values in terms of reasonable print quality range. On a perspective the analysis finds that vegetable oil (soya) based inks are a possible innovation to replace Petroleum based systems which have a high quality of prints and are useful in making a practice of offset printing a responsible effort to the environment.