Evaluation of circular and low impact denim acid washing processes using handmade composite stones

Purpose This study aims to evaluate the performance and sustainability of handmade stones (HMS) as an alternative to conventional pumice stones in acid washing of denim fabrics. The research investigates the effects of treatment type on fabric structural properties, mechanical performance, surface morphology, stone durability and environmental impact, with particular emphasis on statistical validation of fabric mass (GSM) changes. Design/methodology/approach Denim fabrics were acid-washed using both pumice stones (AP) and handmade stones (AH), and their physical, mechanical and environmental performance was evaluated. Fabric properties including GSM, ends per inch (EPI), picks per inch (PPI), tensile strength and tear strength were measured using standard test methods, while a scanning electron microscope (SEM) was used to examine surface morphology. Stone durability was assessed through Los Angeles abrasion and crushing value tests. Environmental impact was determined by analyzing wastewater parameters such as total dissolved solids (TDS), turbidity and chemical oxygen demand (COD). One-way analysis of variance (ANOVA) was applied to evaluate the effects of different treatments on GSM and related structural characteristics. Findings One-way ANOVA revealed a statistically significant effect of treatment type on GSM (F(1,16) = 47.54, p < 0.001), with AH-treated fabrics (365.83 ± 3.24 g/m²) showing significantly higher mass per unit area than AP-treated fabrics (359.67 ± 0.82 g/m²). The large effect size (η² = 0.75) indicated that 75% of GSM variation was attributable to treatment type. Increased GSM in AH samples corresponded with higher EPI and PPI values, confirming fabric compaction rather than material deposition. Mechanical property losses remained within acceptable limits (≤15%) for AH, whereas pumice-treated samples exceeded the 20% degradation threshold. SEM analysis demonstrated more uniform fibrillation and reduced fiber damage in AH-treated fabrics. Durability testing showed minimal deterioration of HMS compared to pumice, and wastewater analysis revealed lower TDS, turbidity, COD and environmental impact measurement scores for HMS, indicating reduced environmental burden. Research limitations/implications This study did not evaluate the long-term effects of HMS on industrial washing machinery. Although HMS exhibited higher durability than pumice stones, their potential impact on machine wear and tear (e.g. drum, paddles and internal components) during prolonged industrial use remains unknown. In addition, the number of experimental runs was limited to avoid excessive machine wear, operational costs and production downtime associated with repeated acid washing trials. Therefore, future studies should investigate the long-term reusability of HMS and its effects on machine maintenance, equipment lifespan and large-scale industrial performance. Originality/value This study provides statistically validated evidence supporting HMS as a sustainable and performance-efficient alternative to pumice in denim acid washing. By integrating structural, mechanical, morphological, durability and environmental analyses with robust statistical validation, the research advances sustainable finishing technologies and offers an industrially scalable solution aligned with cleaner production principles.