I have entered a pastel era with my textile work. Pastel shades are easy enough to achieve with most natural dyes by simply using less dyestuff in an immersion dye bath, but with indigo it’s trickier. One quick dip in a medium strength vat might yield a light blue shade but it won’t be stable or even. When working with indigo the best most stable and even results are achieved by dipping the fibers in the vat several times to build depths of shades. In my book Farm & Folk Quilt Alchemy I share my go to method of setting up a medium strength organic fructose indigo vat and maintaining the vat for several months. With this method medium and dark blues are achieved at first, and then over time as the indigo pigment gets taken up by fibers, light blue shades can be achieved. If you desire dark and medium indigo shades and you don’t mind waiting for those light blue shades, this method is great.
Recently I’ve found myself in some situations where I need light blue shades but don’t have a vat that’s yielding them yet. I began experimenting with setting up weak vats and I’m excited to share that I’ve had success achieving stable sky blue shades right away. Of course there’s a slight downside to the weak vat. I normally maintain a 30 gallon medium strength fructose vat for a year or longer and a 5 gallon size vat for at least 6 months but I’ve found that a 5 gallon weak vat will crash pretty quickly after only a month or so. Of course this makes sense because there’s not much pigment (or other ingredients) in the vat so they get used up quickly. The upsides, besides the instant sky blue shades, is that a weak fructose vat is quick and easy to set up, it requires minimal ingredients, and like all organic vats, can be neutralized and composted when it stops yielding color.
The following recipe is for a 5 gallon size vat. Due to the high pH (12) of the fructose vat this recipe is best suited for cellulose fibers. A pH above 10 may damage protein fibers. Be sure to wear a mask when weighing ingredients and setting up the vat to avoid breathing in the fine indigo and calcium hydroxide particles. Wear gloves when dipping fabrics to protect your hands from the high pH vat environment. A 5 gallon bucket or a 20 quart stainless steel stockpot make great vat vessels. The vat will need to be reheated every time you use it. If you don’t have a submersible bucket heater use a pot that can be warmed on the stove.
Wetting out the indigo pigment with hot water and a mortar and pestle.
Weak Fructose Indigo Vat
30 Grams indigo Pigment
60 Grams Calcium Hydroxide (lime)
90 Grams Fructose
18 Quarts Hot Water
1) Measure out the water and bring it to a near boil on the stovetop, then turn off the heat. Weigh out all the remaining ingredients.
2) Wet out the indigo: I do this with a large mortar and pestle. If you don’t have one use a plastic container such as a water or shampoo bottle from the recycle bin. Add the indigo pigment and a small amount of the hot water. Shake vigorously for 5 minutes then add it to your vat vessel along with about 4 quarts of the hot water.
3) Wet out the lime: add 2 quarts of water to a container and whisk in the lime until there are no lumps. Pour this solution into the vat vessel then add another 2 quarts of the hot water.
4) Wet out the fructose: add 2 quarts of water to the same container you used in the previous step and stir until the fructose is dissolved, then pour it into the vat.
5) Add the remaining hot water to the vat. Stir with a broom handle, large dowel or spoon in a circular motion creating a vortex for about 3-5 minutes. A cluster of bubbles (a flower) will likely appear at the center surface of the vat. Put a lid on the vat then wrap it in several old towels or blankets (or whatever you can come up with) to keep it insulated and warm as it reduces overnight.
Dye
The next day the vat should be reduced and ready to dye. I like a vat temperature of about 85-90ish degrees. If it’s too hot unwrap it and give it time to cool. If it’s too cool warm it up with a bucket heater or on the stovetop. When the temperature is good gently submerge an old upside down colander or anything like that and situate it in the bottom of the vat to prevent your fabric from stirring up the sediment at the bottom. The reduced vat liquid should be a clear amber or yellow-greenish color. Indigo dyeing does not require a mordant before dyeing but be sure to scour your fabric. For the best most even results with a 5 gallon vat I recommend dipping pieces of fabric no larger than a half yard at a time. Read through the instructions before beginning so you’re set up with everything you need.
1) Wet out your fabric in warm water with a tiny pinch of soda ash for about 5 minutes. Wring it out and give it a good shake out so the fabric is opened up and not folded onto itself.
2) Gently submerge the fabric in the vat trying your best not to introduce oxygen to the vat by creating bubbles. Gently move the fabric around being careful to keep it fully submerged for 3-5 minutes. Smaller pieces don’t need to be dipped as long as larger pieces. I dip half yard pieces for 5 minutes. Gently wring out the fabric while it’s still beneath the surface to create less bubbles.
3) Plunge the fabric into a bucket of cold water. Open it out and rinse vigorously to create lots of bubbles. Then hang it on a line out of direct sunlight to continue oxidizing for at least 10 minutes.
4) Each piece should be dipped a total of 3 times. Wait about 10-15 minutes between dips then repeat steps 1-3.
Entering fabric into the vat for a second dip.
Neutralize
Indigo dyed fabric needs to be neutralized with vinegar so the color doesn’t crock. Neutralizing also eliminates the chalky alkaline feeling left on the fabric after dyeing. Use about 2 tablespoons of 5% strength white vinegar per gallon of warm water and soak the fabric for about a half hour. Rinse in cold water. Hang the fabric to dry, then store it flat out of direct sunlight for at least a week before doing the final rinses with warm water and a pH neutral detergent. Continue rinsing the fabric in lukewarm water until the rinse water is clear or nearly clear.
Linen fabric after 3 dips in the weak indigo vat.
I hope this helps if you’re trying for some light blue indigo shades! If you need more information about dyeing cellulose fabric with indigo please see formula 7 in my book Farm & Folk Quilt Alchemy (also available wherever books are sold). In that section you will learn all the details about how I maintain my fructose vats. Be sure to tag me if you try this recipe. I sure do love to see what you’re creating. Cheers!
