Today thanks to help from Debbie and Jane and Leena I managed the fructose indigo vat.
I heated 3 litres of water to 80 degrees C, tipped the contents of the little 400ml vat in and stirred. Within 30 seconds flakes of blue appeared on the yellowy looking surface then a thick blue indigo flower. After ten minutes the colour of the water under the filmy surface was a lime green then a orangey yellow. ( the colours of this type of vat seem different to that of the chemical reduction vat using thiourea dioxide.
Nb It would seem that you can make a stock solution just as we do with the thiourea vat which could I think be very useful