1st Inaugural Indigo Apprenticeship Blog Series Entry #2 by Amanda Gough

Image of the submerged indigo after 2 days of soaking by Amanda "Ama Liza" Gough

This blog series includes three different pieces written by Amanda "Ama Liza" Gough, AFA and Indigo Shade Map Intern & Apprentice.

Preparing to remove the indigo leaves by: Amanda "Ama Liza" Gough

Blog 2 of 3

The Alchemy of Color: Soaking, Sliming & Stirring into Blue

In this second entry of our Indigo Apprenticeship series, we explore the aromatic and transformative next phase of fresh leaf extraction. After harvesting and sorting our indigo (Persicaria tinctoria), we shift into an alchemical process that spans several days, requiring patience, observation, and respect for timing and sensory cues.

Apprentice Susan Tuberville removing the leaves from the containers. photo by: Amanda "Ama Liza" Gough

Stage One: Soaking the Leaves in Water (Fermentation)

Once your fresh indigo leaves are harvested, cleaned you will submerge them completely in a large vessel of clean, room-temperature water. You will leave this in a secure container outside in the warmth. Check daily, observing changes in color and smell.

Over the course for a couple of days, you’ll notice the water darkening from greenish to a distinct turquoise-teal hue. This color presents almost neon. This color shift indicates the water-soluble precursor to indigo (indican) is beginning to break down.

Tips for Check Point #1

Visual Cue: The water turns turquoise.

Tactile Cue: Leaves feel slimy to the touch.

Olfactory Cue: The Smell of Putrid Death

Once indigo leaves are removed after the quick ferment. photo by: Amanda Gough

At this point, the fermentation has broken down the cell walls of the leaves, releasing the indigo precursors into the water. Remove the leaves. If left too long, the fermentation can “overcook,” degrading the indigotin and affecting yield. We suggest composting the putrid leaves.

Master Indigo Dyer Rosa Chang examined the container to confirm it was ready to go through the next process by: Ama Liza

Stage Two: Letting the Pigment Settle (Reduction Preparation)

After removing the leaves, allow the remaining liquid to sit undisturbed for more days secured in the heat.

Tips for Checkpoint #2:

Visual Cue: A shimmering film forms on the surface of the liquid. This film indicates that the fermentation process has completed and the pigment is ready to be fixed with an alkaline material.

Olfactory Cue: The aroma thickens brace yourself

The blue film that resides once the solution is ready to go through the aeration process. Photo of Stern Jenkins Volunteer-Apprentice by : Amanda Gough

Stage Three: Adding Alkaline (Calcium Hydroxide / Pickling Lime)

First add a little of the indigo solution to the bowl with the lime to help it dissolve. You should see it turn blue slightly before adding it into the bath.

Indigo Master Rosa Chang adding the calcium hydroxide (pickling lime) to the solution accompanied by Apprentices Amber and Mimi . Photo by Amanda Gough

Now, slowly stir in calcium hydroxide (pickling lime) to raise the pH and precipitate the pigment.

Add in small increments, stirring constantly, until the liquid reaches a right pH level.

This addition prepares the bath for oxidation, which transforms the reduced indigo into visible, insoluble blue pigment.

Apprentice Amanda Gough participating in the aeration process, everyone took a turn. Photo by : Amber Likins

Stage Four: Aeration (Oxidizing the Indigo)

Immediately after adding lime, begin aerating the vat vigorously stirring continuously. Wear clothes that you don't care get stained and stinky.

Rosa Changs hand after touch testing the turquoise bubbles during the aeration process. Photo by: Amanda Gough

Tips for Checkpoint #3:

Visual Cue:

• Bubbles appear as you agitate the vat. The should go from white bubble to  turquoise bubbles and then blue bubbles.

• Liquid shifts from teal to deep blue.

• Foamy blue bubbles begin to form and cluster at the surface.

Auditory Cue:

• A subtle carbonated “fizz” or crackling sound often accompanies the final phase of pigment oxidation this is a signal you’ve reached peak transformation. Stop agitating the solution now.

Successfully oxidized indigo colored bubbles. Photo by: Amanda "Ama Liza" Gough

Stage Five: Rest and Settle

After aeration, cover the container and allow it to sit undisturbed for more days to let the pigment particles settle at the bottom.

The color of liquid that is ready for the resting period. Photo by: Amanda Gough