Sustainable discharge printing of marigold‐dyed cotton with eucalyptus wood ash extract and its optimisation by response surface methodology

Abstract This study investigates the use of wood ash extract as an alkali in the discharge printing of natural marigold‐dyed cotton fabric. Wood ash was extracted in an aqueous medium at 90°C and was used to prepare printing pastes at concentrations of 10%, 20% and 30% (w/v). Marigold dye was extracted from flowers, and cotton fabric was dyed with the extract. Discharge printing was optimised using response surface methodology (RSM), considering variables such as wood ash extract concentration, temperature and steaming time. The effects on discharging efficiency were analysed, and the process was statistically optimised. Elemental analysis of the wood ash extract revealed high concentrations of potassium, contributing to its strong alkaline nature (pH 10.2‐11.4). RSM optimisation showed that the highest discharging efficiency was achieved with 20% wood ash extract at 100°C for 5 minutes. The discharging efficiency model was significant ( P < 0.05), and validation experiments confirmed the model's accuracy. The predicted and experimental discharging efficiencies were closely aligned, demonstrating the effectiveness of the wood ash extract in discharge printing. The study presents a sustainable method for discharge printing using wood ash extract as an alkali on marigold‐dyed cotton fabric. The optimised process achieves high discharging efficiency while reducing the environmental impact. This method highlights the potential of wood ash as a valuable resource in eco‐friendly textile processing, promoting greener practices in the industry.