Degumming Silk Cocoons

After the moths emerge, the cocoons must be degummed before they can be spun into yarn.

Degumming is the process of removing the sericin, a sticky substance produced by the silkworm that holds the strands of silk together.

Each cocoon is surrounded by short threads that the silkworm used to support its structure. These threads tend to be of inferior quality so it's best to remove them before degumming. They pull off quite easily.

The support silk can be degummed and used if you like, but I usually don't bother with it.

Next, the larval and pupal skins must be removed from the inside of the cocoon.

A pair of hemostats comes in handy for this step.

Filling the cocoon with water makes the skins float to the top and also prevents them from crumbling inside.

Fill a pot with water and add a generous amount of soap--about 1/2 cup per 100 cocoons. It's important to use only natural soap instead of detergents which may contain enzymes that can harm the silk, or sodium lauryl sulfate which is harmful to you. Some recipes call for washing soda and/or lye but I've gotten good results using only soap.

Simmer the cocoons until they collapse onto themselves and lose their shape. This can take anywhere from 30 minutes to several hours depending on the specie of silk.

Make sure the cocoons do not boil as this can cause them to tangle up and mat.

When they look like fluffy cotton balls they are sufficiently degummed.

Protein fibers do best in an acid state so add a splash of vinegar or acetic acid to the final rinse water. About 1/4 cup per gallon of water.

Rinse and gently squeeze out the excess water and hang to dry.

They will look matted up when dried but you should be able to pull them apart with your fingers and fluff them. If not, then repeat the degumming process.


They are now ready to spin.

Copyright Pam DeLuco. All rights reserved.