Tuesday, March 22, 2011

Pink Silkworms!

If you've been to sheep & wool shows or seen colorful silk cocoons for sale on line (like the ones I dyed here), they are cocoons that have been dyed AFTER the cocoon was spun. And, importantly to the fiber artist, the dye will disappear from these pretty little cocoons once you enzymatically remove the sericin (the substance the worm ejects along with the silk protein to makes the cocoon hard and help protect the worm from predators while it develops into the moth). And you'll be left with either white or tan cocoons, depending on whether the cocoons dyed were the cultivated Bombyx Mori (bright white) or cocoons of the wild type moth (which eats leaves with tannin in them so the silk they spin is "discolored" a lovely earthy tan color). But now the Singapore Agency for Science, Technology and REsearch has come up with a way of integrating the color into the actual protein as the cocoon is spun! So the cocoon is colored and the silk remains colored after removing the sericin. Even the worm turns the color of the dye it is going to produce (see photo below)! I'm not sure how I feel about this advance in fiber technology yet. The aim is to reduce the need to commercially dye silk to make it cheaper and I suppose this might be a better thing for the environment? Anyway... this week a customer (whose husband is a chemical engineer, I believe) brought in an article from one of his trade journals about introducing fluorescent rhodamine dyes in with the mulberry leaves so that the worm eats the dye right along with the leaves so the dye molecule is actually integrated into the fibroin protein of the silk and becomes a permanent aspect of the silk fiber. The range of colors so far developed are nothing to write home about (in my mind, anyway) and the story is still out on whether the color will be light fast and also whether the integration of the dye into the protein molecule changes the strength, sheen, or softness of the natural silk. But I thought it was interesting to know about, so thought I'd share it...

And by the way, if you want to learn more about how silk is harvested from cocoons or how to knit directly from the coccoon, I have more information here on the website. Here are a few last photos of some 8th generation Vermont silk cocoons I raised here a few years back!