Jul . 22, 2024 10:02 Back to list

Maintaining and Troubleshooting an Organic Indigo Vat

The questions I receive most frequently about natural dyeing seems to center on the indigo vat and its maintenance. Since 2011 I have been making and using organic indigo vats, an art and skill that I learned from Michel Garcia.

My current vat began in a 5 gallon vessel over 2 years ago. I enlarged it to fill an 8 gallon vessel, and then last year I enlarged my vat again to fill a 30 gallon container. The increased size was needed because I was dyeing larger pieces of cloth.

my current indigo vat, 30 gallons — My 30 gallon indigo vat

The vat was made using henna as a reduction material. I chose to use this material because the slow release of sugars is good for a vat that will be maintained for a long time. I add fructose after each use and additional henna when I need to boost the reduction. Lime (calcium hydroxide) is the alkaline.

The vat is used regularly and I achieve excellent color from the indigo. The large size challenges me to solve problems as I encounter them. It would be tempting to discard a small vat that was not behaving well and begin again, but emptying this vat would require a great amount of effort. As a result I’ve learned a lot about maintaining the indigo vat.

indigo blue vat blue

An indigo vat is happiest when it is used on a daily basis. After each dyeing session I “feed” it with a bit of fructose, stir it to bring the un-reduced indigo and reduction materials up from the bottom, check the pH, and let it rest for a few hours before dyeing again.

Occasionally I run into problems that I need to solve. Recently I was away from home for several weeks. Before I left, the vat was dyeing rich, deep blues. The color of the vat was a golden bronze and there was a good healthy “metallic” sheen on the surface and plenty of bubbles.

surface of a healthy vat — Surface of a healthy vat

When I returned home the first thing I did was add lime to the vat. When an indigo vat sits dormant for any amount of time it becomes more acidic and the pH goes down. I can test this with pH papers but a good visual indicator is to sprinkle some lime on top. If the lime is immediately “sucked” down into the vat – you can assume that the vat is in need of the lime. If the lime just sits on the surface, the pH is probably fine.

Next, I stirred the vat and waited for it to settle. The color of the vat looked good, as well as the surface. The vat was a clear gold color and there was a coppery sheen on top. But the first test sample resulted in barely any color at all! That was a surprise, since I thought there was plenty of indigo in the vat. I thought I had also been “feeding” it with plenty of sugar. The vat had been used very heavily before I went away. I thought that possibly the indigo had finally been exhausted.

Before adding more indigo to the vat, I decided to add more sugar – a generous amount. Once added, the vat was stirred and I waited until the next day to do another test strip. It produced a blue, though it was relatively light. I repeated the sugar-stir-rest and dyed again the next day. It was darker. I repeated the sequence again, and finally got back to a shade of blue similar to that which I had before going away.

The lesson here is that before adding indigo to a vat, test it thoroughly for pH and reduction. Although it “appeared” to be healthy, my vat was not reduced and the indigo wasn’t available to dye the fibers.

MORE THAN ALL YOU NEED TO KNOW TO MAKE YOUR OWN INDIGO DYE VAT

How to Balance a Fructose Indigo Vat