(a) one for evaporat-ing under reduced pressure with a rotary evaporator, and (b) onefor dyeing. The crude dye extract obtained from the rotary evapora-tor was dried and then stored in a desiccator before use. To obtain astandard calibration curve, the crude dye extract was later groundand diluted with distilled water. The dilution of the mangrove barkextract showed a relatively clear solution with a linear depen-dence on the concentration–absorbance relation at an absorptionpeak (max) of 278 nm. The concentration of 15 g L−1was calcu-lated from a standard curve of concentrations of the mangrove barkextract dye solution versus absorbance at the wavelength men-tioned.