How to extract pigment from fresh indigo:
* Harvest + extract on the same day for best yield
* Bundle stems into bunches and gently give them a quick rinse. Avoid bruising leaves to increase pigment yield.
* Place bundles in a bucket, fill with water, and weigh bundles down with clean, large stones to ensure the leaves remain in the water.
* Cover and leave out in the sun for a couple of days.
* The water will begin to turn murky green as the leaves ferment and then neon blue-green once it has neared completion of fermentation.
* Once a coppery, metallic sheen appears on the surface, remove the leaves and strain plant material.
* Add calcium hydroxide (about .5 gram per gallon) and use an immersion blender (or pour back and forth into two buckets). Aerate the solution for at least one minute and then wait a few minutes. Blend and wait again. Repeat. Check the pH. It should be around 11. Add more calcium hydroxide if it’s too low.
* Once the liquid turns blue, the indoxyl has turned to indigotin and the vat is ready. Allow to settle. Oxidation is complete when the pigment settles to the bottom and the liquid turns yellow or reddish brown.
* Carefully decant the liquid off. Avoid disturbing the pigment that has settled at the bottom.
* Line a mesh strainer with a paper filter and place in a bowl. Carefully pour pigment in. Once the liquid has drained, rise pigment with water.
* Dry fully.
* To remove dried pigment from the filter, hold the filter in your palm and pull the edges together with your other hand. Keep the edges closed while you carefully crinkle the filter together, releasing the pigment from the paper. Open carefully and pour into a jar for storage.
* To make paint, use roughly equal parts pigment to gum arabic. Grind pigment with a mortar and pestle into a very fine powder. Add a few drops of distilled water and mix into a paste. Add gum arabic until well blended. (Use a glass plate and muller for finer, less gritty results.) Scrape into a jar and add a couple of drops of clove essential oil or a clove bud to help preserve.