Spinning polyphemus silk

This is the process I use for degumming and processing the Polyphemus wild silk cocoons into yarn. There are a LOT of photos (26 more) under the cut.

These are the cocoons. Because they have all hatched, each one has a hole in one of the ends where the moth emerged. The moth secretes an enzyme called cocoonase which dissolves some of the silk; the silk around the hole is often brittle because of that.

This is a single cocoon, slit down the side so that you can see the pupal shell inside. The shell and a shed caterpillar skin remain after the moth emerges; it is flaky and very thin, and it’s difficult to get it out of the yarn if it gets in there. It’s much easier to take it out now, before the simmering.

Here, you can see the damaged edge where the cocoonase dissolved the silk so the moth could dig its way out.

I’m trimming the tip of the cocoons. This enlarges the hole, and wastes a little bit of silk, but it does a lot of good in terms of allowing me to clean out the cocoon, and getting rid of any of the brittle silk.

The cocoon doesn’t really lose a lot of silk.

I dig the pupal shell and caterpillar skin out with the tip of the scissors. The inside of the cocoon is very smooth, and feels like brown paper bag, only much nicer.

See, all nice and clean now!

The trimmed cocoons. These are from moths that I raised over the past couple of months. There are about 25 of them in the bowl.

I start the kettle for the degumming bath. Per gallon of water, the solution contains 1/4 cup of Orvus paste and 1/4 cup of washing soda. I bring the kettle just to a boil, then turn it down to low so that it will stay hot, but not bubble at all. It should be below 185’F.

The cocoons naturally tend to float, until they get wet.

Once they’re wetted through, they sink, or float just below the surface. As long as they’re all wet, it’s OK. I use a slotted spoon to press them down to make sure they’re all wet.

This batch degummed very quickly. It can take up to an hour, but these were ready in about fifteen minutes. I think that getting all the crud out, and opening up the cocoons, made them go a little faster.

They’re ready, when the cocoons can be easily pulled apart like this. There may be a few little spots that are still tough, but carding takes care of most of that.

The degummed cocoons.

I strain them in a sieve, and rinse thoroughly until they stop sudsing.

Then, I rinse again with a little citric acid, and then with Milsoft fabric softener. The Milsoft makes a HUGE difference in the ease of working with the silk; it makes the fibers slide and handle nicely.

This is after the fiber has been squeezed out. I often press it between paper towels to help get the moisture out.

The fiber is a mix of long and short fibers. The long fibers can be many yards in length; before the moth busts out, the cocoon is a single filament with no break, hundreds of yards long. The short fibers are from the cut edge. The short fibers would have been there whether I cut it or not, though, as long as the moth emerges.

This is after the silk has dried. It’s about a third of an ounce.

I start carding. I use the tips of the carders, almost more like combs. This allows me to get the best quality silk.

After running the cards through the silk a few times, I start tugging out the long fibers. This is similar to making roving from combs, although I don’t pull it into a solid length, I make little tufts, like locks.

This is one of the little tufts. The fibers are at least four inches or so in length. If there is a lot of silk that is more than six or so inches, I will sometimes cut it to be more even.

I build up a little pile, and then put a twist into it to make a little “soldier” – these are what I’ll spin from to make the best yarn.

The short bits and noils are caught in the teeth of the carder. I card these together with the shorter fibers to make a very light rolag. This spins up into a much lumpier, but still usable, yarn.

The carder with some of the processed silk.

The edge of a rolag, and a pile of the little spinning soldiers.

I made just a couple of quick samples with the silk. On the left is the fine yarn – about a 2/50’s or so. The combed fibers are easy to use to spin a very fine, even shiny yarn. On the right is the noil yarn, made from the rolag.

20 replies
  1. mothie
    mothie says:

    Waste not wnat not. 8-] I love your little soldiers. Beautiful yarn. What do you do with this spun yarn? Weave?

    I’m currently spinning Maine Coon cat combings for a friend. She saved them for 10 years — that’s a lot of fluff. I’ve gotten over a dozen skeins so far, with just a few more to go.

    The things we do for entertainment. ;-]


  2. admin
    admin says:

    I want to make some yarn (probably a leeetle thicker than this sample) and knit an amulet bag on OOOO’s. I may end up using some of this to weave, but the problem is getting enough to warp up with!

  3. admin
    admin says:

    Ironically, the better at it I get, the more it looks machine-made.

    But yes – all the wild ones have a lot more character!

  4. admin
    admin says:


    I don’t sell the cocoons – it’s just too much of a pain in the behind to raise them! I’d be more than happy to give you some eggs, though, if you want some.

  5. Anonymous
    Anonymous says:

    Alas, I’m not in a good situation to raise moths right now, which is too bad because it’s been something I’ve been looking into lately. We live in a very small basement. Maybe sometime in the future. Thanks! -Kat

  6. eahhh
    eahhh says:

    Oh my gosh, what a beautiful tutorial. You really have a gift for presenting information in an absorbing way. I can scarcely believe that crunchy, dull little polyphemus cocoons turn into something so glistening and tempting. Three cheers for your hobby and skill!

  7. mama_bel
    mama_bel says:


    what happens to the new moths? are they in an enclosure, or out into the local area? I looked them up- is the silk different if they feed on different trees?
    Hey- that would be a cool science-fair project! Who could we talk into it?

  8. admin
    admin says:

    Re: curious

    The females I put out in a mesh cage in the yard, and local males fly in and breed with them. The males, I release.

    Food definitely influences the silk. The color is from tannin, and they will eat a variety of plants with different amounts of it.

  9. chessiekitty
    chessiekitty says:

    I always love reading your posts. You do a great job of explaining what’s going on in a way that’s easy to understand and enjoyable to read.

  10. Anonymous
    Anonymous says:

    amazing silk

    Oh Michael!! your silk is so beautiful!!! I am looking forward to trying it myself. What a privledge it is to know these little beings .

  11. Anonymous
    Anonymous says:


  12. niamh_sage
    niamh_sage says:

    Ok, this is going to be convoluted. I found my way here from ‘s journal, in which posted a comment linking both your LJ and your photo essay on the life cycle of Hyalaphora cecropia.

    I just wanted to say, WOW. A wonderful record of the life of an amazing and gorgeous creature. Beautifully done. And having popped into your LJ and seen the article on producing silk from cocoons…WOW again.

    Would you mind if I added you to my flist? (I read your warning – I’m not afraid of language or graphic dreams.)

  13. hellebelle
    hellebelle says:

    hi, i found your blog through your post about the sock monkey in . i’d just like to say that i think it’s so great that you raise your own months and then let them hatch and then use their cocoons. i went to china last summer and visited a silk factory, where i saw workers boil cocoons alive. it made me feel a bit sick.

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