DHAKA – Researchers from Bangladesh have successfully dyed cotton fabric using seawater. The scientists dyed two batches of cotton fabric, one using salt water collected from the Bay of Bengal off the South East coast of Bangladesh and the other using standard groundwater. They then compared the finished results in areas such as shade difference, reflectance, colour strength, wash, rubbing and colour fastness. They found that while the seawater fabrics were slightly lighter in shade in comparison, they achieved satisfying results across all of the other parameters – opening up the intriguing possibility of sea water fabric dyeing being carried out on a broader scale.
The results present some fascinating possibilities for the notoriously thirsty global textile industry. Indeed in Bangladesh, where he research took place, groundwater levels have been falling at an alarming rate as boreholes are drilled every deeper to access water – the primary feedstock for the country’s mammoth wet processing sector. The PaCT: Partnership for Cleaner Textile programme in Bangladesh has claimed that some local textile mills use 250 – 300 litres of water/per kg of fabric, which is notably above internationally recognised standards.
In their work, the researchers compared change in colour or colour fastness after washing using reactive dyed ground and seawater samples and found that there was “no significant difference for the samples.”
In terms of rubbing fastness – how well dyed fabrics withstand rubbing or staining – it was found that seawater dyed samples achieved superior results to their groundwater dyed counterparts, while both samples illustrated an excellent ability to withstand perspiration.
Only in the area of colour shade did the sea water fabrics fall down, with seawater dyed samples notably lighter in shade than ground water dyed samples. This, in theory, could mean there are limitations on its application to industry use. The researchers also note that further work is needed to examine the cost effectiveness and logistical feasibility of using seawater for fabric dyeing on a wider scale.
The paper is written by Israt Zerin, lecturer, Department of Textile Engineering, Southeast University, Bangladesh.
The full paper Dyeing of Cotton Fabric with Ground water & Sea water appears in the Journal of Polymer and Textile Engineering.