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  • Writer's pictureDavid Connolly

DyStar's Denim Dyeing Process Environmentally Sound

Updated: May 27, 2021

Chemical supplier DyStar shared the results of an independent test that looked at the environmental impact of its indigo dyeing process.

In a presentation at Kingpins24, DyStar explained how its Cadira Denim System eliminates the use of hydrosulphite, which is responsible for salt formation during the denim dyeing process. The resulting salt generated in conventional dyeing processes can make its way into natural water supplies and degrade the ecosystem.

Using the Cadira Denim System, DyStar replaces hydrosulphite with its organic reducing agent Sera Con C-RDA and combines it with DyStar Indigo Vat 40% Solution to create what it calls the “cleanest indigo on the market.”

An unnamed customer, DyStar said, independently tested the solution and compared it with two other indigo dyeing solutions: the conventional process, which uses indigo powder and requires large amounts of hydrosulphite in both the preparation and dyeing stages; and DyStar Indigo Vat 40% Solution, which is pre-reduced and only requires hydrosulphite in the dyeing process.

It found a significant reduction in the amount of sulphites in the wastewater of the conventional (27,084 mg/l) methods compared to pre-reduced (3,250 mg/l) methods and the solution that includes Sera Con C-RDA (133 mg/l). Overall, the Cadira Denim System reduces sulphites and sulphides by 98 percent.

The test also found that the system reduces the chemical oxygen demand (COD) and the total dissolved solids (TDS) by 88 percent and 93 percent, respectively.

Aside from having a lesser effect on the environment, the Cadira Denim System also introduces a unique palette of shades and wash-down effects as a result of the different chemistry and application.

Author: Liz Warren

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