Fiber Friday - Silk from Seed to Skein

Silk - an incredible fiber with an amazing historic tradition. Lately there has been a ton of hype about 'sustainable' and 'eco-friendly' fibers, and as a fiber fanatic, I really can't help but feel that there's been some unfairness to our natural protein fibers - silk and wool - which have nearly always (when avoiding irresponsible practices such as overgrazing) been both these things, for many thousands of years. But before I am distracted by that topic, let's focus on silk.

The practice of 'growing' silk is called sericulture. According to traditional legend, silk fiber was discovered when a cocoon dropped into the cup of a Chinese princess, who, in the process of plucking it out of her cup, started unreeling it. Whether or not this is really how it all began, the basics of raising silkworms and reeling cocoons hasn't changed drastically in the 4700 or so years since sericulture began.

Silk begins as a simple 'seed' or silkworm egg. These have been inspected (or their parents) to ensure they are free of disease and kept in cold storage until the time is right (the food supply is adequate, for example) for them to be hatched.

The hatched larvae are placed on screens with huge amounts of chopped mulberry leaves, where they eat around the clock for about six weeks. Then they stop eating and start looking for a place to spin their cocoon. I've seen the cocoon nesting frames - they look like a cardboard grid. these are rotated as the silkworms will climb upwards to find their chosen square in which to anchor themselves and start spinning.

Some silkworm cocoons will be set aside to be used to produce breeding moths, and the remainder will be stifled to prevent the cocoon being torn apart by an emerging moth. Did you know that silkworm pupae are eaten? So nothing goes to waste. The moths that are allowed to emerge will breed, lay eggs and die, starting the life cycle over again.

The cocoons are placed in hot water, where the air is mostly removed by weighting them to submerge them. The cocoons are brushed to remove the undesirable outer layer (used to make various by-products and lesser quality fabrics, such as noil). Then the true filament can be found. A private silk grower has a great website that shows this reeling process. Filaments from multiple cocoons are reeled together to create a filament thread or yarn. This is traditionally wound into skeins and sold as raw silk. Raw silk is often erroneously used to describe certain fabrics. Well, not entirely wrong - as presumably those fabrics still have a large amount of sericin, or 'silk gum' left in the fabric. But in the industry, raw silk refers the the skeins of filament that are ready to be incorporated into the weaving process.

There's much, much more to all this than what I've mentioned here. If you Google 'sericulture' you will find various links, such as this one, which will give you a little more information. It's a fascinating subject. I have the great good fortune to have been invited to join a sericulture tour of Japan next May. I'm pretty darn excited about it! I am sure I'll have a lot more to tell about the amazing world of sericulture after that.