Creating your own Japanese indigo dye from your home-grown Japanese indigo is not as hard as it might sound!
Japanese Indigo is from the Polygonaceae family and grows best in hot or humid climates. However it may be cultivated in colder climates, as long as it is protected from frosts.
The plant can also be grown indoors or in a hot-house inside a pot. This makes it a great dye plant for cooler climates, with an extended growing season. Japanese indigo can be annual, biennial or perennial depending on where it is grown. However note that when grown in cooler climates, the seeds must be harvested each year and replanted the next growing season.
The plant is visually attractive with soft, medium green leaves and pale pink or white flowers that appear in Autumn. It will grow up to 2 meters tall.
Once you have an established plant you can propagate others by bending a soft branch and inserting it into the soil, whilst leaving it attached to the main plant. This will reshoot into a new bush!
To check when your indigo bush is ready to use for dyeing, just crush a leaf between your fingers. When it leaves behind a blue stain it is ready to harvest and be used in your dye vat!
Extracting the Indigo Dye
The beautiful rich blues of Indigo dye come from the leaves of the plant.
- To make your indigo dye vat, strip the leaves from the stems and squash them into a container. Use a glass jar, enamel or stainless steel pot. Cover the leaves with water.
- Place your jar into a larger pot on a trivet, or use a double boiler. Fill with water to at least halfway-up the container that has the indigo leaves in it.
- Slowly raise the temperature until it reaches 160c. Control it at this point but do not let it get any hotter than 180c. Alternatively you can fill your waterbath with hot tap water and leave until it cools down. Repeat this a few times. The dye will be a brown color with a tinge of blue in it.
- Strain out the leaves retaining the liquid dye. You can do this by placing a piece of cheesecloth into a strainer over a bowl and pouring the liquid through this. Squeeze the remaining liquid out of the leaves to extract as much color as possible.
- To create the beautiful blue color you need to change the pH of the dye. Do this by adding some soda ash or ammonia, until you reach pH 8-9. You can test this on a piece of litmus paper. See more about the changing the pH of dye vats here.
- The dye vat now needs to be aerated and this can be done in a number of ways. The easiest way is to use an electric whisk however you can also use a manual whisk or simply pour the dye back and forth between one contained and another. This process will take approximately 10 to 15 minutes with an electric whisk or longer if using a manual method. You are looking for the dye to foam up, turn blue and then finally green.
- The dye pigment now needs to be extracted from the liquid dye you have created. This is a difficult and time consuming step. Leave the dye bath to settle for a few days and then – very gently – using a ladle, scoop the clear (it will have a bluish tinge) liquid from the top. Try not to disturb the settled pigment at the bottom of the pot. Each time the pigment is disturbed it will take several days to resettle. Eventually you will be left with a blue sludge at the bottom. This is your Japanese indigo dye. You can dry this to create a powder that can be stored for future use.
- Another option (rather than the step above) is to use your dye bath immediately. However you must first remove the foaminess of the indigo. This can be done by adding Sodium Hydrosulfite at a rate of 1/2 teaspoon per gallon of dye.
- Stir gently being careful not to add anymore air into the dye vat. It can take a little while for the dye to reduce and change color.
Dyeing with Indigo
Now you have been through the painful processing of extracting the dye, you are ready to get down to the actual business of dyeing!
- Thoroughly wet your yarn, fleece or fabric and gently squeeze the excess water out.
- Gently immerse into the warm dye bath and move around carefully under the surface – so as to not create any more foam.
- Leave in the dye bath until the desired color is achieved. A rich blue can usually be seen in approximately 20-30 minutes. The materials will change in color from yellow to green and then blue.
- Remove your dyed material from the vat and gently squeeze to remove excess dye. Rinse with tepid water, remembering not to change the temperature of your yarn or wool too quickly or you risk it felting.
- You can continue to dye using the same dye bath. You will get varying shades of lighter blues until the dye bath is completely exhausted.
Creating Japanese indigo dye is a time consuming and difficult task!
There are many suppliers of natural dyes that have already gone through this laborious process for you. So if you love Indigo but can’t be bothered with the extraction process above then consider buying some online!