Indigo Fermentation Vat Dyeing

Definition and Overview

Indigo fermentation vat dyeing is the process of adding sukumo, the raw material for natural indigo, together with wood ash lye, lime, and other materials, and using fermentation to reduce the indigo pigment into a dyeable state. Reduction means changing the indigo pigment, which is difficult to dissolve in water, into a form that can penetrate fibers.

Fibers dipped in the dye bath appear yellow-green immediately after being lifted out, then turn blue as they are oxidized by exposure to air. To achieve depth of color, dipping and oxidation are generally repeated. Indigo fermentation vat dyeing does not refer to the name of a dye color; it refers to the technique of preparing and maintaining the dye bath.

Characteristics and Color Appearance

Fermented indigo dyeing is characterized by a deep blue color and changes in color that accompany use and washing. The dye may bond mainly to the surface of the fiber, so it gradually fades through friction and washing, creating a unique appearance for each wearer.

The texture is not determined by indigo fermentation vat dyeing alone. It varies greatly depending on the type of fiber, such as cotton, linen, or silk, as well as yarn and fabric density, number of dyeings, and post-processing. It is important not to treat indigo fermentation vat dyeing as the name of denim or a specific woven fabric.

Main Applications

Dyeing by indigo fermentation vat dyeing is used for shirts, blouses, dresses, pants, and outer layers made with cotton or linen, as well as bags and fashion accessories. If the material and fabric design are selected appropriately, it can be used for year-round items, but it is also often adopted for spring and summer clothing because of its cool-looking color tone.

When planning, in addition to whether it is indigo fermentation vat dyeing, confirm whether the dyeing target is yarn or fabric, what the material is, and the final color tone and how it changes after washing. Even with the same indigo color, the composition of the dye bath and management method may differ from indigo dyeing that uses chemical reducing agents.

• For dark-colored items, assume color transfer to light-colored linings, accessories, bags, and similar items.
• For products that combine multiple colors, check for dye transfer during washing and how the item looks after fading.
• For mass production, confirm the color for each lot to reduce color differences between samples and actual production.

Handling and Sewing Notes

Handle products according to the care label, and for the first wash, wash separately as a rule. Avoid long soaking, strong friction, and the use of chlorine bleach. Leaving items stacked while wet, or allowing them to contact light-colored items while still damp from sweat or rain, can also cause color transfer.

Before cutting and sewing, check the shrinkage rate and skew of the fabric to be used, and if necessary, carry out wetting treatment or trial sewing. Because friction during sewing may make the surface color appear to change, take care to avoid rubbing against the presser foot or worktable, as well as color transfer to white interlining or accessories.

Differences from Similar Terms

Indigo dyeing refers broadly to dyeing with indigo-based dyes and includes methods other than natural indigo fermentation vat dyeing. Indigo fermentation vat dyeing is a term that focuses on the process and technique of preparing and managing the dye bath.

Wood ash fermentation vat dyeing is used as a term for fermented vat dyeing that uses wood ash lye. On the other hand, the meaning of jigoku date varies by region and maker, so for ordering or labeling it is important to confirm the dye raw material, vat preparation method, and dyeing process individually.

Frequently Asked Questions