The dyepot. The actual indigo dye is the clear green liquid, which you can see in the bucket.
Here are the fabrics, ready to go in to the dyepot. There's a silk scarf, and some woolen yarn.
After about three or four minutes in the dye, the fibre is taken out, and it's a bright green colour.
The excess dye is squeezed out, and the fibre is exposed to the air.
As the indigo is exposed to the oxygen in the atmosphere, it turns blue, and also "fixes" to the material. The above two photographs were taken about 65 seconds apart. It's magic!
A silk scarf changing colour as the indigo oxidizes.