Here you can see the madder root, which has yet to break down, under the indigo water's surface the water has a blue foam on the top but has not turned a dark blue yet. This vat requires more fermentation time before it will become usable.

The vat will start out dark blue color you will need to beat air into the vat to get it to reduce at this time. Beating the indigo fermentation vat seems to defy all logic when it comes to indigo dyeing - where you are constantly being told to NOT introduce Oxygen into the vat, this is the one time you get to stir the dickens out of your indigo vat and it results in great colors!

Here the color is beginning to turn a dark pea green color, it needs further reduction so keep stirring until it turns yellow.