The award will go toward the continued study to make dyeing of denim more cost-efficient and environmentally friendly.
The Fiber and Biopolymer Research Institute (FBRI) at Texas Tech University has received a grant of almost $275,000 from the Walmart Foundation that will extend crucial research being conducted to improve the safety and efficiency of indigo dying of cotton yarns.
The grant of $274,999 was announced at the U.S. Conference of Mayors in Washington, D.C. on Jan. 17. The grant goes toward the research project entitled "Foam Indigo Dyeing of Cotton Yarns: Machine Design and Process Control," which received a grant of $472,564 from the Walmart Foundation in 2014.
But due to the unexpected closing of the American Cotton Growers Denim Mill in Littlefield, a partner with the Fiber and Biopolymer Institute in the project, the original timeline was disrupted, which required the vast majority of the original funding. A small-scale system has been created that enables researchers to effectively and precisely control and measure all variables involved with applying foam indigo to yarns, thus requiring the additional funding.
"Indigo, the unique colorant for ubiquitous blue jeans, is a non-toxic, sustainable dye," said Dean Ethridge, a research professor with the Department of Plant and Soil Science in the College of Agricultural Sciences & Natural Resources and former FBRI managing director. "But current dyeing processes require large amounts of time and space, use large amounts of sulfur-reducing compounds, produce large amounts of wastewater and use large amounts of energy. This project aims to eliminate the sulfur compounds, shrink the water and energy requirements by as much as 90 percent, shrink the floor space required for dyeing and enable a three-to-five-fold increase in speed of the dyeing process, all while achieving superior dye uptake and dye fastness."
The project is focused on using foam dyeing of cotton yarns used to make denim instead of the current technology that was developed shortly after World War I. Under current methods, indigo is insoluble until it undergoes a chemical change known as reduction, which is a gain of electrons and a lowering of the oxidation number to impart a negative charge to the indigo, making it soluble in water and able to penetrate fabric.
But when the indigo is removed from the dyebath, it combines with the oxygen in the air and instantaneously reverts back to its oxidized, insoluble form that also leaves behind indigo on the surface that has to be washed, and current technology leaves behind a tremendous amount of wastewater, sulfur-reducing agents and other chemicals.
Foam dyeing is more sustainable and saves a tremendous amount of water, and it is a technology being used around the world. Its use for dyeing denim cotton yarns, however, remains limited. Through this research project, the FBRI hypothesized and demonstrated the ability to break through the barriers limiting foam indigo dyeing that could make it a commercial success by meeting three requirements, according to the project proposal:
- The yarns must be conditioned with an anaerobic "wash" to remove all oxygen possible from around and inside the yarns before going into a dyeing chamber.
- The dyeing chamber must also provide a controlled anaerobic environment that can optimize dyeing efficiency so the technology makes the cost and resource savings so great that adopting the technology ensures a competitive advantage.
- Because yarns are unlike other structured fabrics, there must be adequate control of the yarn orientation for a reliable yarn-to-foam interface.
According to the new proposal, results to date have been very positive, showing an increase in the speed of and ability to repeat the dyeing process, improved dye uptake and fastness, a large reduction in the use of water and energy and an ability to compact the dyeing process so it does not take up a large amount of space. Most importantly, the use of sulfur compounds has been eliminated.
"Dr. Ethridge and the team at the FBRI do outstanding work," said Guy Loneragan, interim vice president for research at Texas Tech. "The new grant continuing their collaborative work with the Walmart Foundation is a testament to the excellence and value of their work. This is a great achievement for the FBRI and for research at Texas Tech University."
In addition to Ethridge, other members of the research team include Noureddine Abidi, FBRI managing director; denim consultant Ralph Tharpe with Indigo Mill Designs LLC; and indigo consultant Howard Malpass.
"The research project of Dr. Ethridge and his team addresses the need for cost-reducing, sustainable dyeing with indigo, which comprises one of the largest single types of dyes used throughout the world today and is of paramount importance for textiles made from cotton," said Steven Fraze, interim chairman of the College of Agricultural Sciences & Natural Resources.
"As one of the world's largest sellers of denim jeans and other indigo-dyed textiles, Wal-Mart's support of this project shows an awareness of need and a desire to help U.S.-based manufacturers reach new levels of efficiency and sustainability," Fraze said. "This college is devoted to the pursuit of knowledge that improves the competitiveness of cotton; therefore, we are especially gratified that Wal-Mart has enabled research offering such great potential for improvement in the manufacturing process."