Waiting 24 Hours Between Mixing and Using Your Indigo Vat

Q: I have a question about the 24 hour waiting period from mixing the ingredients to using the vat. Could you tell me a little bit more about that. Is it necessary? I've used the Jacquard (synthetic) product and was able to use immediately after mixing.

A: In a word, yes. The wait is necessary. There is a big difference between the pre-reduced synthetic indigo and the natural indigo contained in the kit. The synthetic ingredients have already been modified to dissolve in water whereas the indigo in my kit does not dissolve in water. The 24 hour period allows the indigo to a) dissolve and b) become properly reduced (able to transfer onto fabric) and also c) the iron and lime in my kit (the activating ingredients) need time to properly combine. If you dye too soon, you'll get very pale blues and run the risk of staining the fabric brown/sludgy with the iron. If you wait the 24 hours, you'll get great color transfer and no staining.

Scaling Down Vat Size

Q: I purchased your indigo kit and am wondering if there is a way to do a half batch or a third of a batch. I'm trying to dye very small quantities of fabric and don't want to waste any dye.

A: Sure, no problem. You can just scale all of the quantities of water, indigo, lime, and iron in the instructions by an equal amount to make a smaller vat. If you can, use a tall deep container for your partial vat. That will work better than a shallow broad container.

How Much Fabric Will the Natural Indigo & Shibori Dye Kit Dye?

Q: Can you tell me approximately how much fabric one of your Natural Indigo & Shibori Dye Kits will dye?

A: A safe, loose estimate is 10-12 shirt sized garments to a dark shade of indigo. That said, the amount of fabric you can dye with this kit varies widely depending on how thick the fabric is, how dark you dye it, how much of the piece is blue vs white and how well you’re able to maintain the vat health!

Ferrous Vat Longevity

Q: I just purchased one of your Natural Indigo & Shibori Dye Kits. Once I create my indigo vat, do I have to use it right away or does it last for a while?

A: Your vat will last for weeks, once mixed up, if never used. The key to longevity of a ferrous vat is to minimize its contact with air. You should always keep it tightly lidded when it is not in use. And, when you're using the vat, make EVERY EFFORT to not slosh, splash, or drip back into the vat as that will oxidize your vat and leave the indigo pigment unable to bind to fabric. The kit is designed so that the pigment and the ingredients that activate it, should exhaust themselves at the same time.

Once you begin using your vat and it starts to lose potency, you can always rejuvenate it. I go in depth on the process of sharpening your vat on my page about indigo vat basics.

Components in the Natural Indigo & Shibori Dye Kit

Q: What is the component/powder used as a reducing agent in your Natural Indigo & Shibori Dye Kit? How is it different from base? What is the base that can be used?

A: The reducing agent for the vat in the kit is actually the combination of the Ferrous Sulfate and the Slaked Lime. Together they form a molecule which modifies the indigo molecule and causes it to become able to integrate and adhere to fabric. Both ingredients - plus the indigo - are necessary for the reaction to happen.

The base (or basic molecule) in the kit is the calcium hydroxide AKA Slaked Lime. In water, this molecule dissolves and separates into calcium and hydroxide ions, effectively raising the pH (alkalinity) of the liquid. Slaked lime is the appropriate base to pair with ferrous sulfate to create a vat. Do not replace with another base as the reaction will not produce the desired result of properly reducing the indigo molecule.

Indigo Form in the Natural Dye Kit

Q: Is the indigo in your Indigo & Shibori Natural Dye Kit in powder form or paste form? Is it pre-reduced?

A: The indigo itself is in a paste slurry form that has never been dried, so there is no challenge (as there is with fully dried indigo) in getting it hydrated.

It is not pre-reduced which means it needs to be mixed with two other ingredients (included in the kit) that activate the indigo pigment into an indigo dye.

Indigo Kit and Dyeing Large Items

Q: I bought your Indigo & Shibori Natural Dye Kit. Would it work to dye a blanket or other large item?

A: The kit certainly has the ability to dye large items, but it is designed for creating repeat patterns on smaller (or bundled) pieces of fabric by folding the pieces into smaller shapes and dipping those as opposed to over-dyeing large pieces. All-over dyed pieces will tend to be mottled and uneven in the color uptake when dyed in a relatively small amount of liquid like the 5 gallons the kit is designed to produce. When dyeing large items I prefer to dye in vats that are 25-50 gallons and typically larger indigo-dyed items with all-over coverage (like jeans) are dyed in the yarn and then woven. Large items are rarely dyed in natural indigo vats because of the challenge.

Light and Pale Shades of Indigo

Q: What is your recommended amount of indigo for a five gallon vat if I wanted a pale blue, not a dark blue?

A:  The kit comes with a bottle containing 50g of indigo extract. This is plenty to make a very saturated blue dye achievable with only a half dozen dips or so. If you would like a paler blue, it is best to get there with the same number of dips, though each dip will only be a baby step toward deep indigo as opposed to using the full strength of the vat. So, you can mix up the vat as normal (same amount of water, all the iron, all the lime) and simply add 1/4 of the indigo. This will produce a weak vat. When you layer many dips in this vat, you'll get some wondrously rich pale blues. You can save the indigo for later addition or for another vat.

Scent of Natural Indigo

A: A natural indigo vat has a unique smell somewhere between earthy, musty, smoky with a hint of grass and manure!

The indigo pigment that comes in your bottle is actually a fermented extract from a plant. As a result, different seasons and batches of indigo, as well as indigo from other locations will have varying smells. Different vat preparations also create different smells and believe it or not, this vat style, known as the iron vat, has the least smell!

After your dyed goods are rinsed in the citric acid solution and washed, the smell fades.

Dye Vat Capacity

Q: The kit indicates the vat can manage about 5 pounds of items. Can you tell me if that number changes if you are dipping items for longer or more times? So if you dipped 5 pounds of tea towels (for example) 3 times each, would you plan to dye 2 1/2 pounds of tea towels, if you were going to dip them 6 times each?

A:  You’ve got it. The darker you dye your items the less total weight the vat can accommodate. Also, the lighter weight your fabric, the less weight the vat can dye. Also, how well you treat your vat contributes to how much material you can push through it. Also, if you tie your pieces up into small bundles so only the surface gets dyed, you can dye more total weight (with the same amount of surface area). The 5lb measurement is really subjective!

Lightweight fabric has more surface area relative to the total weight of the fabric so actually absorbs more indigo per pound than a thick, heavy weight fabric (which has a much smaller surface area). Thin fabrics can be very taxing on a vat, so the yield per weight numbers don’t really apply to to them. The 5lb weight notation on the kit was initially tested using a medium shade of blue, dyed with shibori patterning that was about 50/50 indigo coverage to undyed fabric on medium weight cotton jersey.