Learning & Knowing | Interventions

How much mordant is being disposed? The measurement and environmental impact of mordanting natural dyes.

Sherry Haar and Kowshik Saha


Sherry Haar is a professor at Kansas State University, exploring scientific and artistic applications of natural dyes, regional fiber, and sustainable burials. Kowshik Saha is a Ph.D. student at North Carolina State University. His MS research focused on mordant measurement and quality.


Despite toxicity concerns of chemical mordants used in natural dyeing, there is limited research on the measurement, quality, and safe disposal of the chemical mordant effluent. Experimental methods were used to measure the distribution of aluminum mordant ions across the premordanding process for wool and cotton using inductively coupled plasma–mass spectrometry and the effluent quality characterized through chemical oxygen demand and total organic carbon. For cotton, most (92-96%) of the aluminum remained in the effluent bath and wool ranged from 26-68% dependent upon fiber and concentration. Findings will be discussed against various input, discharge, and disposal standards and organic certifications to determine the safe use, reuse, and disposal of aluminum mordants.