Vat Recipes

We have tested and written 3 types of easy indigo vat recipes for the home-dyer. Listed below are directions for an Iron Vat, Hydro Vat, and a Fructose Vat. For first-time dyers we recommend using one of our natural indigo kits which align perfectly with our recipes.

Iron Vat 

This recipe is a proven in-house recipe, enjoy!

The iron vat is the ideal recipe to get beautiful saturated blues on cotton, linen, and other cellulosic fibers.  It is not recommended for protein-based fibers, as the iron may cause discoloration or brittleness on these materials.  Once set up, the vat does not require heating and may last for weeks or months when covered and occasionally replenished. To make a vat, you must make a concentrated stock solution containing dissolved (reduced) indigo and then add it to the large vat container in reduced conditions.

Ingredients: All ingredients are based on using a 5-gallon bucket

  • 50g SCC natural indigo of a known purity  
  • 35g Iron (II) sulfate heptahydrate, (FeSO4) also known as copperas or ferrous sulfate
  • 44g Calcium hydroxide (Ca(OH)2), also known as slaked lime or hydrated lime
  • 5 gallon tall and narrow bucket with a lid to serve as a vat container
  • A lidded pot or large jar for the stock solution one fifth to one quarter the size of your vat. A 2 quarts pot to one gallon will serve nicely as a stock pot.

Stock Recipe

Begin by determining the total final volume in gallons of your vat, then measure out the following quantities of each material. The stock solution will be about ¼ to 1/5 the volume of the final vat. 

Use 17g/gallon of Stony Creek Colors Natural Indigo for a very strong vat on cotton. For a slower-building vat, use 9g SCC indigo/gal. The recipe below uses about 13g natural indigo/ gallon. In 100% active indigo this ranges from 3-6 g/gal equivalent. So if you are making a strong 5-gallon vat with 35% purity indigo, use 85g of Stony Creek Colors Natural Indigo powder.

To make a 4-gallon vat from 50g of SCC natural indigo (about 17.5g active dye)

Per 50g natural indigo powder, use 35g FeSO4 and 44g Ca(OH)2.

Paste indigo thoroughly in hot water. Dissolve Ca(OH)2 (also called Hydrated lime or quicklime) in 0.5 L warm water. Dissolve FeSO4 (Iron Sulfate) in .5 - 1 L warm water. Add more water if necessary.

Fill a large container, such as a pot or 2-quart mason jar with a lid with warm water (50C or 120F), leaving room for the above ingredients. Add indigo, then FeSO4, then Ca(OH)2. Let sit with the lid on for 2-3 hours. The stock will change color from blue to yellow or brownish. 

If you purchase a different purity from us or you want a different vat size, calculate inserting your purity or vat size. For example, in the following formula, .35 stands in for 35% purity. You would use 5 gals * 6 g/gal /0.35= 85 grams of indigo powder.  Per g indigo, use 2 g FeSO4 and 2.5 g Ca(OH)2.

Preparing the Vat

Use a container, preferably plastic, that is as tall and narrow as possible. A good container to use is a 5-gallon bucket with a lid.  Fill the vat, leaving enough room for the stock solution, with 100-120 F water.

For the 4-gallon vat recipe above 92g Ca(OH)2 and 30 g FeSO4.  

Per gallon of final vat volume, add 23 grams of Ca(OH)2 and 7-8 grams FeSO4. Paste the lime with water and dissolve the iron in warm tap water, then add the lime followed by the iron to the vat. Stir well then wait thirty minutes to one hour before adding the stock solution.  Avoid stirring roughly and pour the stock carefully to minimize the amount of air that is introduced to the vat. The final color of the vat should be brownish-yellow. Refer to the troubleshooting section if it is not this color.

Allow the sediment to settle completely before using the vat, and take care to avoid letting the fabric touch the sediment.  We like to put a raised stainless metal grating at the bottom of the vat to keep our fabrics off the bottom. If the sediment does discolor the fabric, a good soak in vinegar will sometimes remove the stains.

Maintaining and Troubleshooting the Vat

To keep the vat working as long as possible, stir it thoroughly once per day. If the vat turns greenish, add a maximum of 15g/gal iron sulfate, stir thoroughly, and allow to settle before checking the color again. If the vat turns blue-ish, add a small amount of lime (1-2g/gallon). Again, stir thoroughly and allow to resettle before checking the color.

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Hydro Vat

This recipe is a proven in-house recipe, enjoy!

This is the fastest vat and works well for all types of fabrics. We are using Rit Color Remover as the chemical reducing agent because it is widely available for a gallon vat. You can use hydro or thiourea dioxide if those are more accessible to you.

This recipe is for a 2-gallon vat. You need a pot that holds a minimum of 2.5 gallons to allow room for dyeing.

  • 15 grams powdered Stony Creek Colors 25% natural indigo or 10 grams of SCC 40% indigo
  • 15g of Rit Color Remover (contains Sodium dithionite also known as hydrosulfite)
  • 4 grams of Sodium carbonate for wool or silk and 10g for cotton
  • 2 gallon of water

Vat Instructions:

  1. Scour fabric: scouring is a hot water wash that removes industrial sizing, dirt, waxes, oils, lanolin (wool), sericin (silk) and pectic substances (plant fibers) from your substrate to be dyed. For plant fibers use 2 tsp synthrapol or detergent (neutral soap) and 8 tsp soda ash (alkaline surfactant) per pound of fiber. Add scouring agents to your very hot water wash in a machine, or to a clean pot of very hot water (above 160 degrees F) and let scour for an hour while stirring. Scouring ensures even take up of the dye. Fabrics sold as “Ready for Dyeing” sometimes do not need to be scoured. Animal fibers like silk and wool are usually best scoured by hand using Orvus Paste (1 tsp per 1 lb fiber being dyed) or gentle soap with hot water that doesn’t exceed 160 degrees F so as not to damage or felt the fibers. You can scour a bunch of materials at once and do not need to dye them all right away. Just make sure they are dry before you store them.
  2. Pre-wet the indigo in the quart jar mix the indigo with enough water to wet it out entirely getting rid of gritty clumps. An easy way to hydrate the indigo is to add it to water in a glass jar with a tight-fitting lid and some marbles and shake well for a few minutes. If you do this, we suggest you remove marbles before dyeing.
  3. First, you will make a “stock solution”. Add the pasted indigo and ½ of the sodium carbonate to a quart jar and fill about ⅓ of the way with ~140 F water.  Make sure both powders are thoroughly mixed and then fill jar nearly full with more hot water. Sprinkle in ¾ of the Rit Color Remover, stir gently and screw the cap onto the jar. Let the stock solution sit to reduce for at least fifteen minutes. You should see the color go to green or yellow. It is a good idea to place this mason jar upright and sealed into a larger container in a case it leaks. Placing into warm water will help speed up the reaction. If after 15 minutes you slowly turn and rotate the jar and see a lot of settled indigo or while at the bottom, gently rotate to try to get that indigo into suspension.
  4. Meanwhile, fill pot with just under 2 gallons of water at about 120F-140F (remember you still need to add your 1-quart stock solution to this pot). Room temp water is fine but may take slightly longer to reduce. Add remaining Rit Color Remover and sodium carbonate. Target pH of your vat should be around 10 after stock is added. If you aren’t getting close to that add more sodium carbonate. Prepare the vat by adding the remaining Rit Color Remover to the vat vessel with 120-140 F water.
  5. Add the stock solution to the vat vessel (2.5-gallon pot). Stir gently without splashing and wait 10-15 minutes for it to go fully into reduction.

To Dye:

  1. Wearing gloves, pre-wet scoured material with water then submerge the materials into the vat carefully. You want to minimize the amount of oxygen you are adding to the vat by adding slowly and not lifting up and down a lot. To get your materials more evenly dyed, we suggest gently rub the material with your hands staying submerged below the surface for a few minutes. if you are dyeing shibori or tied garments and not worried about levelness, you can place them in there and fish them out when ready.  For ALL indigo dyeing, regardless of vat type, you want to build up color through successive dips. Start with longer dips (5-10 minutes) and then follow up with shorter dips (30 seconds - 1 minutes) to deepen the shade. Then, taking care not to agitate, stir or drip back into the vat, remove the materials.
  2. As the materials are being removed let them drip into a nearby bucket. The indigo rich contents of the bucket can be recycled back into the vat when you recalibrate it for later use.
  3. Allow a minimum of 10 minutes and a max of 30 minutes between dips so the fiber can fully oxidize with the material hanging in a shady spot. When you’re happy with the depth of color. Remember some of the indigo will rinse off, and that plant fibers such as cotton tend to dry a few shades lighter than their color when wet. So, if you love a color you have reached in the vat, at least dip it one more time! If you want a very light color for your final garment, make the vat less strong by adding less stock, and do shorter dips. You want at least three dips even if they are short.  Rinse in cool water until to get a lot of the unfixed indigo rinsed off.
  4. For the integrity of the fiber, add a bit of vinegar or citric acid to the final soak to neutralize the alkalinity of the calcium hydroxide  (especially for animal fibers like wool and silk). Then rinse again! Indigo may still rub off so we would suggest being careful with your first few times wearing the garment to not sit on any white couches.

Want to dye something bigger? For A 10 Gallon Vat You Will Need:

  • 70g 25% SCC indigo
  • 70g Rit Color Remover
  • 18g sodium carbonate for wool or silk and 26g for cotton
  • 1-quart jar for stock solution
  • Use a 10 gallon (40 quarts) stainless steel pot and use 9 gallons of water for your vat which can be found online or most big box stores.

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Fructose Vat

This 1-2-3 vat recipe is courtesy of Liz Spencer aka @thedogwooddyer, enjoy!

Ingredients:

Included in Kit:

  • 100g powdered Stony Creek Colors 25% natural indigo 1 part
  • 200g calcium hydroxide 2 parts which is an Alkaline/Base
  • 300g fructose crystals  3 parts which is a Reducing Agent

Not Included:

  • For plant fibers use 2 tsp synthrapol or detergent (neutral soap) and 8 tsp soda ash (alkaline surfactant) per pound of fiber
  • 5-gallon stainless steel pot which can be found online or most big box stores
  • 1 tsp of Orvus Paste per 1 lb wool or silk fiber being dyed

If you use paste do a 2-2-3 method which means using 200g of paste

This recipe will dye up to a kilo (2.2lbs) of fiber a dark blue, and there will also be enough indigo left to dye other items a slightly lighter shade. This vat recipe is based on the traditional indigo vats of Morocco, India, and Provence and was developed and revived by Michel Garcia. It relies on the chemical reactions between a mineral alkali and a natural reducing agent to remove excess oxygen (a chemical process called reduction). Reduction takes the oxygen from the indigo dye molecule liberating and allowing it to be soluble in water and to attach and bond to fibers. Natural reducing agents absorb oxygen and are known as antioxidants. They include dried and fresh sugar-rich fruits, minerals, flavonoids, medicinal plants, and even other dye-plants and substances (henna, dates, iron/ferrous sulfate/copperas, yeast). Without a reducing agent and alkaline substance, the indigo would not dissolve in the water and would remain suspended and unavailable for the fiber to access.

 

Instructions

  1. Scour fabric: scouring is a hot water wash that removes industrial sizing, dirt, waxes, oils, lanolin (wool), sericin (silk) and pectic substances (plant fibers) from your substrate to be dyed. For plant fibers use 2 tsp synthrapol or detergent (neutral soap) and 8 tsp soda ash (alkaline surfactant) per pound of fiber. Add scouring agents to your very hot water wash in a machine, or to a clean pot of very hot water (above 160 degrees F) and let scour for an hour while stirring. Scouring ensures even take up of the dye. Fabrics sold as “Ready for Dyeing” sometimes do not need to be scoured. Animal fibers like silk and wool are usually best scoured by hand using Orvus Paste (1 tsp per 1 lb fiber being dyed) or gentle soap with hot water that doesn’t exceed 160 degrees F so as not to damage or felt the fibers.
  2. Bring water in large pot 2/3 full to 120 degrees.
  3. While you wait for the water to heat, mix the indigo with enough water to wet it out entirely getting rid of gritty clumps. An easy way to hydrate the indigo is to add it to water in a glass jar with a tight-fitting lid and some marbles and shake well for a few minutes.
  4. Add this indigo solution to the hot water in the pot, then stir in the calcium hydroxide.
  5. Finally, add the fructose and stir well.
  6. The vat may take up to 45 minutes to be ready and sometimes takes overnight to reduce.
  7. Wearing gloves, submerge your pre-wet materials in the vat carefully and gently rub the material while submerged for a few minutes. Then taking care not to agitate, stir or drip back into the vat, remove the materials.
  8. As the materials are being removed let them drip into a bucket nearby. The indigo rich contents of the bucket can be recycled back into the vat when you recalibrate it for later use.
  9. Allow up to half an hour between dips so the fiber can fully oxidize with the material hanging in a shady spot. When you’re happy with the depth of color (remember some of the indigo will rinse off, and that plant fibers such as cotton tend to dry a few shades lighter) rinse in cool water until there is no longer any indigo rinsing off. For the integrity of the fiber add a bit of vinegar to the final rinse/soak to neutralize the alkalinity of the calcium hydroxide  (especially for animal fibers like wool and silk).