1st Inaugural Indigo Apprenticeship Blog Series Entry #2 by Amanda "Ama" Howard

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

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

Preparing to remove the indigo leaves by: Amanda "Ama" Howard

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 pigment 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" Howard

Stage One: Soaking the Leaves (Fermentation)

Once your fresh indigo leaves are harvested and cleaned you will submerge them in a large vessel of clean, room-temperature water. You will leave this in a container outside. 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 teal hue. 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 "Ama" Howard

At this point, the fermentation has broken down the cell walls of the leaves, releasing the indigo precursors into the water. 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 photo by: Ama

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 film forms on the surface of the liquid. This film indicates 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 : Ama Howard

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

First add a little of the indigo solution. You should see it turn blue slightly before adding it into the bath.

Indigo Master Rosa Chang adding the calcium hydroxide to the solution accompanied by Apprentices Amber and Mimi . Photo by Ama Howard

Now, slowly stir in calcium hydroxide to raise the pH and precipitate the pigment.

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

Apprentice Ama Howard 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 bath 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: Ama Howard

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.

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

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 Howard