Abstract:
This research aimed to investigate: 1) methods for extracting powdered dye from longan leaves for printing on cotton fabric, 2) suitable printing formulas, 3) types and concentrations of mordanting agent, 4) testing the colorfastness and physical properties of the dye and 5) designing prototype products for screen-printed fabrics using longan leaf powdered dye.
The research method involves extracting longan leaf powdered dye by boiling 1kg of finely chopped longan leaves with 5l of water for 2h, followed by filtering out the residue. The resulting dye solution was then mixed with maltodextrin, and subsequently dried thoroughly using a hot air oven. After that, the dye solution was ground finely with a grinder until it became powder. For determining suitable printing formulas, the experiment was planned using a factorial design in a completely randomized design (CRD) to investigate three factors: the ratio of finished printing powder to longan leaf powdered dye at three levels (70:30, 80:20, and 90:10), dye fixation times (5 and 10 min), and dye fixation temperature (120and 150 degree Celsius). Two types of mordanting agents, alum and iron rust, at two concentrations (5 and 10 g/l of water) are considered. Colorfastness and physical properties were tested as per ISO and ASTM standards, and satisfaction with the prototype products was surveyed.
The study results revealed that the method of extracting longan leaf powdered dye from water mixed with maltodextrin yielded a fine powder with a brownish-yellow color. The optimal printing formula consisted of 70g of finished printing powder and 30 g of longan leaf powdered dye, with a fixation time of 10 min at a temperature of 150 degree Celsius, resulting in a color strength (K/S) of 1.21. The fixing agent providing the best color strength was found to be alum at a concentration of 5g/l of water, yielding a K/S value of 2.01. Iron rust at a concentration of 10 g/l of water produced a K/S value of 3.40. Colorfastness and physical property testing revealed that the colorfastness to water, perspiration, and rubbing was rated as good to very good. There was a slight increase in fabric stiffness after printing. Moreover, upon designing prototype products such as laptop bags from screen-printed fabrics using longan leaf powdered dye, it was found that consumers expressed a 90% satisfaction rate and interest in purchasing the product.