I decided today to process the cocoons of my Samia ricini x walkeri. There are not that many of them, but they range in colour from bright white, through beige, to golden orange. I really like the golden orange ones, but I wasn’t sure whether that colour would remain in the silk. In some of the silkworm varieties with bright yellow cocoons, they still produce white silk, because the colour is in the sericin (the glue that holds the cocoon together) rather than in the silk filament.
Here's what I'm starting with.
The first step is to clean out the cocoons. Although the moths have emerged, this doesn't mean the cocoon is empty. Inside is the shed skin of the caterpillar, and the empty pupal case. Its a bit fiddly opening up the cocoons and removing all the detritus, but if you leave it in, then you end up picking bits out of the silk all the way through the process, so the cleaner the cocoons are at the beginning, the better. You can see some of what I’ve removed in this picture.
It doesn't really matter if you cut open the cocoons to remove the bits inside, because its not essential to keep the fibres unbroken. I start the process of making the silk by putting the cleaned cocoons into a saucepan of hot water, with a bit of stergene and washing soda added. I then push the cocoons under the water to get them really wet, bring the water to the boil and simmer very gently. Some people say you shouldn’t boil the silk, but especially with the wild silk, nothing much seems to happen if the water doesn’t get sufficiently hot.
The cocoons will start to soften and loosen, and if you push a kebab stick in, you can see the fibres unravelling and the cocoons breaking down into a mass of threads.
When they get to this stage, I rinse them out in warm water to get rid of the soap and washing soda, then give them a final rinse in some water with citric acid added to it (or you can use vinegar instead)- this is to neutralise the alkalinity of any washing soda that might be left behind. At this point, it looks and feels really soft and, well ... silky!
After rinsing, I squeeze the excess water out and leave it to dry. It doesn’t look quite so appealing at this stage. I am a little disappointed that I have lost that really bright orange colour - its mostly a mix of pale gold, ivory and white.
I am going to leave it now to thoroughly dry out, before moving on to the next stage, turning it into carded fibres and silk thread.