Like most other fabrics, silk is colored with dye. Unfortunately, the dyeing process results in wastewater laden with toxins. Now, however, scientists from the National Chemical Laboratory in India are developing an alternative. They're feeding dye to silkworms, which in turn are producing pre-colored silk fibers.

The researchers sprayed or dipped mulberry leaves in seven types of azo dye, which is the dye family most commonly used in the food and textiles industries. Those leaves were then fed to Bombyx mori silkworms.

Of the seven dyes, it was found that three ended up making their way into the worms' silk, causing it to take on the color of the dye. None of the dyes appeared to affect the worms' health.

Silkworms that consumed Direct Acid Fast Red azo dye produced these red fibers

This isn't the first time that silkworms have produced colored silk after eating dye, although the type of dye used in previous efforts was reportedly too expensive for commercial use. Azo dyes, by contrast, are relatively cheap.

A paper on the research was recently published in the journal ACS Sustainable Chemistry & Engineering.

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