Indigo Dyeing (through the lens of high school chemistry )

A couple of years ago, I wanted to know more about what was happening with indigo "dyeing" (it's really using a pigment as it is not water soluble). I don't really buy the idea that it's "magic";  it is chemistry

(Here's a sample with shibori stitching technique done at Daufuskie Island a couple of years ago):

So, I did some research and thanks mostly to wikipedia came up with the following 

Indigo pigment is derived from indican, a compound found in leaves of various plants including Indigofera tinctoria, Indigofera suffruticosa, persicaria tinctoria (Japanese indigo) and isatis tinctoria (woad). The leaves of the indigo plant contain very small amounts of indican, 0.2 to 0.8 %.  

Indican is a colorless, water-soluble derivative of the amino acid tryptophan. Indican readily breaks down in water (“hydrolyzes”) to release β-D-glucose and indoxyl.

 

Plant leaves are soaked and fermented to produce the blue residue containing indigotin/indican. For shipping or forms of storage, the precipitate from this process is mixed with a strong base such as lye, pressed into cakes, dried and powdered.

 

Indigo is a challenging because it is not soluble in water (it cannot dissolve in water; this is why it is not a dye). To be dissolved, it must undergo a chemical change or “reduction” in which oxygen is removed from the water containing indigo powder. Reduction converts indigo into "white indigo" (leuco-indigo). When a submerged fabric is dipped in removed from the bath, the white indigo quickly combines with oxygen in the air (oxidizes, which is the opposite of reduction) and indoxyl reverts to the insoluble, intensely colored indigo left on the fabric (or paper).  Thus, what is dipped in the bath must be done so carefully in order to not introduce oxygen from the air into the bath.

And...there you go.