Production of Pigments from Purple Potatoes for use in Screen Printing

Abstract

This research aims to study the production of purple sweet potato pigment powder for screen printing using the initial pigment extraction process, which involves extracting purple sweet potato with ethyl alcohol, adding maltodextrin to the resulting purple sweet potato extract to aid in color absorption, and then drying it. The dried extract is then ground into a powder and sieved thru a 400-mesh screen. Five different ratios of purple sweet potato pigment powder to medium were tested for screen printing ink. Screen printing was performed on white cotton fabric, and the printed fabric was measured for CIEL*a*b* color values to determine color difference. The results showed that the ratio of purple sweet potato pigment powder to medium at 40:60 yielded the best print color. The prints were then tested for color fastness to dry and wet rubbing, and color fastness to washing. The results of the dry rubbing color fastness test showed slight to no color bleeding. The wet rubbing color fastness test showed slight color bleeding. The washing color fastness test showed a slight change in color from the original. Therefore, it can be concluded that purple sweet potato can be used to produce pigment powder that yields a purple color when mixed with a medium and can be used as screen printing ink.