How to Dye with Indigo
by Ash Logan
Indigo dye comes from two different plants: genus Indigofera tinctoria (tropical) and Persicaria tinctoria (temperate). The plant is naturally cultivated in India, China, Japan, Egypt, parts of Africa, and parts of the Americas. The dyeing process requires fermentation of the plant leaves with a base and a reducing agent that allows the dye to bind to the cloth. The indigo plant is unique in the range of blue hues it is able to produce. The precise colour of blue depends on the strength of the dye vat and the number of times the fabric is dipped in the vat. Indigo dye will only work with cellulose and protein fibres including wool, silk, cotton, hemp, nettle, and natural rayon.
Cloth has chemicals and different residues on it from the manufacturing process. It is important to clean the fabric so that the dye can penetrate the fibres. To scour, start with boiling fabric in a stainless steel pot. Alternatively you can use a tub or bucket with the hottest water from the tap.
Three components are needed to build the indigo vat: calx or lime, fructose sugar or fruit, and the indigo powder or leaf.
Directions for an 8 L vat:
Shibori tying and binding practices originate from Japan. There are several ways to tie or bind the fabric to create unique patterns. Tools that can be used are rubber bands, clothes pins, string, stones, or wood in combination with folding or tying the fabric around objects. Avoid using aluminum because it can affect the health of the indigo vat.
The fabric should be wet with warm water before dipping into the vat.
Oxygen is a necessary component of the indigo dyeing process – this is where the blue colour will come to life. Oxidization can be achieved through either air or water. If using water, submerge the fabric in cold water for at least 10 minutes. If using air, simply hang outside out of direct sunlight and let the fabric dry. To achieve a darker blue, repeat steps 4 and 5 until reaching the desired shade.
1. Once desired shade is achieved the fabric should soak in a diluted vinegar bath. The ratio should be 15 ml of vinegar to 1 L of water.
2. Rinse with water and dry fabric completely.
3. Soak fabric in soap and vinegar solution.