good morning. It's Kojima.
I was sorting out the photos, and I found a photo of the vegetable dyeing the other day, so I posted it. This is the place where the vegetable broth is collected.
There are many methods of natural dyeing. For the time being, I will explain the reaction mechanism of vegetable dyeing and indigo dyeing.
As you can see in the photo, the vegetable dyeing is steaming. You put plants in hot water to make a broth, put things in it and let the colors soak in, and use a mordant to fix the colors.
I will introduce the mechanism of vegetable dyeing when the indigo dyeing series is over.
Today, I will explain the mechanism of indigo dyeing in a little more detail.
Roughly speaking, indigo dyeing is done by fermenting without applying heat and reacting with oxygen in the air to cause redox and color development.
Indigo, which develops a blue color, has a complex structure (a compound with a heterocyclic ring), so it does not dissolve in water. Basically, it's the same as oil.
Indigo's melting point (the temperature at which it changes from solid to liquid) is 390 degrees, so it is difficult to melt. Even if it succeeds in melting, the heat will damage the clothes (laughs).
However, people in the past succeeded in indigo dyeing through trial and error.
This method used fungi to reduce indigo to a different substance called leuco body, and succeeded in indigo dyeing.
Indigo + reducing bacteria → leuco bodies (water-soluble)
This leuco body is a substance that dissolves in water without applying heat. It is not great? The mechanism that indigo, which does not melt unless heat is applied to 390 degrees, is quickly dissolved in water by bacteria. I simply thought it was great.
This leuco body dissolves in water and is absorbed by clothing.
By the way, the leuco body has a yellow color.
When it comes out of the liquid and comes into contact with oxygen in the air, it oxidizes at once.
Leuco body + oxygen in the air → indigo (insoluble in water)
A beautiful indigo blue coloration occurs.
I'm impressed that people in the past didn't understand chemistry, but they got to this point.
In summary
Indigo + reducing bacteria → leuco body (reduction)
Leuco body + oxygen in the air → indigo (oxidation)
It's a simple two-step reaction.
Actually, it would be better to write the chemical structural formula and explain it, but I'm sorry that I can't write it.
If you would like to know more about the event, please feel free to ask questions.
The charm of natural dyeing is endless.
A limited number of tie-dyed handkerchiefs dyed with genuine indigo by Ms. Yukari Saka are now on sale.
Pint! Indigo Dyed Organic Linen Handkerchief Hotaru
Kojima