Indigo Fermentation Vat

I have been busy organising my work room over the last week, so haven't had much time to do any real "work" such as weaving, spinning or dyeing. But I need to make an indigo fermentation vat so that I can dye some yarn next week. I have to start now, as it takes about 48 hours to work, so that it will be ready for Monday.

It's the ammonia/yeast vat that I am going to make and this is how I am going to do it:

• add 5 tablespoon of powdered Yeast and 5 rounded tablespoons of Sugar to 5 cups (200ml) warm water and leave for 2 hours.
• at the same time dissolve 5 level teaspoons of Indigo to 2 and 1/2 cups (500mls) Ammonia.
• After the 2 hours add the indigo and ammonia to the yeast-sugar mix in a large container and fill to about the 2 1/2 gallon mark. Cover with plastic wrap and use a rubber band to seal. (The fermentation can burst a rigid seal.)
• Leave to sit for several days in a warm place.