According to the information Michael Garcia gave us at ISEND this is a vat that should works so today I decided to have a go.
For some mad reason I mixed 25 g of natural indigo into a paste-I should have mixed up 10 g.
I started at 12 noon
I put about 6 litres into a small stainless steel pot at 50 degrees and 1 tablespoon of calcium hydroxide . This gave a pH of 10-11. I know Michael started off with a high pH
I also heated the vat as I think he started off with a hot vat and cooled it .
I added 2 tablespoons of fructose
After an hour the vat showed signs of slight reduction but dyed some cotton a very peculiar green .
The temperature rose to 65 degrees but the smell of a vat coming into order went and it had an odd smell. The vat looked milky with grains of undissolved indigo on the surface.
I tried removing some of the vat and adding thiourea dioxide which reduced the vat very quickly and dyed a sample a nice blue so I knew the vat was okay I just need to make the fructose work,.
Indigo grains had disappeared there was film on the surface but the ph dropped to 8-9.
a piece of cotton dyed a very pale blue. Hooray I thought I am cracking it!
I left it for a bit and went back but the pH had dropped further to pH7
At 5.30 I added 1 tablespoon of calcium hydroxide. I added 75g of fructose , there was a film on the surface the vat looked a slightly murky yellow and gas was coming off the surface. I dyed some cotton a very pale blue and some linen a patchy green with some very pale patches.
However then the vat seemed to go off.
I finally upended the remainder of the fructose into the vat so I had altogether added 250g (meaning all this was very expensive vat) and left some linen in. This dyed a dark green oxidizing in the air but not to a full blue.
I am puzzled.