Colorful Silks, Naturally

Wild Silk Cocoons
Domesticated silk (top)
compared to different hues of
wild silks (below) 
photo by Biswarup Ganguly

Based on the number of BeWeave It’s dedicated to the subject, 2013 seems to be the year of the silkworm. We’ve talked about how scientists have bread silkworms to produce glow-in-the-dark silks, how researchers at MIT used silkworms to build a beautiful silk dome, and even the culinary uses of the silkworm. Today, we have one more exciting advancement to add to the list: silkworms that produce colored silks.

Biologists and engineers at the CSIR-National Chemical Laboratory in India wanted to find a more environmentally friendly way to dye silk that wouldn’t require a lot of water, either. So they experimented with feeding silkworms mulberry leaves that had been dipped in azo dyes. Previous experiments had been done elsewhere that had shown silkworms would produce colored silks when fed specific dyes, but the dyes used were very expensive. Azo dyes, in contrast, are much more affordable.

While seven different dyes were tried only three resulted in colorful cocoons and only one color remained after the silk was processed, a red dye that resulted in a lovely pink silk. (It also turned the silkworms the same pink, as you can see in the photo montage here.)

Even though only one dye was successful, the researchers learned a lot about how the silkworms' bodies handled the different dyes.  They’re using this information to help with further experiments, so don’t be surprised if in the future you can buy silks spun by worms every color of the rainbow. Until then, if you want naturally colored silks, consider looking into wild silks which come in a variety of hues from off white to golden yellows, as shown at left. 

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