Craft · 6 pages · 12 min
Why indigo dyeing looks yellow in the vat
In the vat, indigo is reduced to a soluble yellow form that turns blue only after air hits the cloth.
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From the opening
Blue indigo is a pigment that will not dissolve in plain water, so a cloth soaked in a blue bath would only stain on the surface. In the dye vat the same molecule is reduced to a soluble yellow form that can soak into the fiber. The opening covers reduced indigo is yellow, air brings the blue back, and pigment locks in the fiber.
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Inside
- Reduced indigo is yellow
- Air brings the blue back
- Pigment locks in the fiber
- Unreduced pigment will not dye
- Where the idea stops applying
- A distinction worth keeping
Sources
- Leuco-indigo in the dye vat
- Air oxidation of indigo