Day 5 - 6: Alkalization + Aeration
Since the indigo fermentation was slow , after consulting with Liz Spencer (The Dogwood Dyer) we decided to try the hot water extraction method. The soaking solution with the indigo leaves was heated up to 50C for 2h. After 2h the solution showed a mermaid teal color and it was removed from the heat source. The leaves were removed, and calcium hydroxide was added to the solution, starting with 2 TBS at the time, until the pH reached 10. Then, the solution was poured from a bucket into another repeatedly for about 10 minutes (about 50 times) to incorporate oxygen and encourage the indoxyl to transform into indigotin. The solution started to look dark and and murky from the pigment precipitation.
The soaking solution of the indigo stems was discarded, the extraction was restarted with hot water (50C) and left to soak for 24h. After removing the indigo plants, the same alkalization/aeration process was repeated with the extract solution from the indigo whole pant.