The Fructose Vat
Review the instructions for indigo vats. Don’t forget to scour your cloth or yarn before dyeing.
For a vat of about 8 litres
— 30 g (1 oz) powdered natural indigo
— 90 g (3 oz) fructose
— 60 g (2 oz) calx (calcium hydroxide)
Fill a 10 litre (2.5 gallon) stainless steel vat 3/4 full with hot water.
Add the fructose and stir to dissolve.
Add the indigo to the vat. Sprinkle on the surface of the vat and stir in until well mixed.
Add half the calx (reserve the second half if you need to raise the pH). Sprinkle on the surface of the vat and stir the vat gently. Do not whip it. You do not want air in the liquid. Wait for a few minutes. Then stir again. Repeat this stirring three or four times.
Heat until the liquid reaches 50°C (120° F). You may then turn off the heat. In about an hour the vat develops a bronzy surface and a small dark blue indigo flower. The interior of the vat will be a clear yellow green.
Follow our How to Dye With Indigo instructions.
Fructose can be used to quickly build a strong vat. However, it has been our experience that fructose vats can also collapse easily or be difficult to revive. For this reason we recommend making a smaller vat when using fructose. A smaller vat also uses less indigo and so (if your vat collapses) there is less dye wasted. We have also found that fructose from fruit works well, whereas commercially available fructose from corn is less effective. Sucrose (refined table sugar) is not a reducing sugar and so will not work.
The next day this vat will benefit from being heated to 50°C (120° F) before use.
Maiwa has a Fructose Kit with everything you need to make this vat.