Indigo Dyeing Safety Instructions

Indigo Vat Safety Instructions


Lye Handling Instructions
NEVER add water to Lye (Sodium hydroxide). You will create a dangerous reaction doing so. ALWAYS add your Lye (Sodium hydroxide) to “cold” water.

Once the Lye is added to the “cold” water the water will become very hot from the chemical reaction! This reaction will cause your utensils and vat container to become hot. Have hot pads or insulated gloves for handling hot equipment.

Make sure that your container can withstand high temperatures.

Read safety instructions that came with your Lye (Sodium hydroxide).

Lye (Sodium Hydroxide) is dangerous! Extreme caution must be used when handling lye (Sodium hydroxide). Lye (Sodium hydroxide) will cause serious burns to the skin, eyes and mucous membranes.

A respirator is required when handling lye(Sodium hydroxide) products as inhalation of the fumes can cause serious burns to the nose and mouth (mucous membranes)

Wear protective gloves, such as latex or nitrile gloves, when handling lye (Sodium hydroxide). Lye (Sodium hydroxide) can cause serious burns to the skin, especially if your skin is moist! The lye (Sodium hydroxide) will start reacting with the moisture on your skin immediately, causing serious burns.

NOTE: Make sure that your gloves are proper fitting, and not too lose, as an ill fitted glove can lead to accidents.

Wear safety goggles/glasses when handling lye (Sodium hydroxide)! This is to prevent any of the lye liquid/fumes from entering the eyes.

NOTE: Do not touch your face, eyes, or ears when handling lye (Sodium hydroxide) products!

Wash your hands thoroughly for five minutes, and upper arms, after working with lye (Sodium hydroxide). You want to make sure that your hands are completely free of chemical before touching any other parts of your body to prevent burns.

Do NOT use with aluminum or cheap stainless steel containers or utensils. Do NOT put lye into an a cast iron pot!

FIRST AID: wash burned area with cool water for 15-20 minutes. Call or seek emergency help for burns. Seek medical attention immediately.

If swallowed seek medical attention immediately. Do NOT induce vomiting!!!

Keep Lye (Sodium hydroxide) away from children and small pets.

IF a spill should occur sweep of lye and dispose of down the sink drain with copious amounts of cold water.

This ALSO applies to Thiox, Indigo extract, Soda Ash or any mordant, assist, or chemical when you are working in the studio.

Thiox will burn your skin wash immediately with water.

Work in a well ventilated area, I prefer to work out of doors with the wind blowing away from me.

Wear a respirator when working with Natural Dye Extracts, Mordants, and Dye Assists


Rather using a studio dedicated teaspoon place your thiox into the indigo vat.

Indigo Dyeing using a Lye or Soda Ash vat

Dye Materials Needed

1 ounce Indigo extract or Indigo chunks
1 cup Soda Ash or Lye (I HIGLY recommend using Soda Ash NOT Lye~!)
2 Tablespoons Thiourea dioxide or Thiox

Equipment needed:

Respirator – you only get one set of lungs! Wear a respirator when handling dye powders, mordants, and dye assists~!
Gloves – wear heavy duty kitchen or dyeing gloves when handling the indigo ingredients (See safety Instructions Below)
Stock Pot 18 quarts or bigger, can be Stainless Steel or Enamel the indigo vat will react with aluminum so I don’t recommend using aluminum pots for creating the vat.
Scale for weighing dyes and chemicals – again studio dedicated!
Measuring spoons, measuring cups, wisk for stirring
Jar – wide mouth pint jar for making indigo paste
Spoon, studio dedicated, for stirring the vat
Tongs for retrieving your fabrics, fibers, etc.
Lingerie bag for small items you wish to find in the vat again the bag makes them easier to retrieve
Water for your vat, rinsing, and for oxidizing
Vinegar – helps to restore the pH balance of wool and silk fibers/fabrics
pH papers/strips for testing the pH of your vat.
Heat source
Clothesline for hanging fabrics onto to help fabric oxidize faster.

Natural Indigo Chemical Reduction Mini-Vat Instructions:

1. READ Safety Instructions before Beginning the Indigo Vat!

2. Fill your vat container with water you don’t need to heat the vat at this point. ALLOW TO SIT OVERNIGHT, doing this allows the oxygen to dissipate from the vat.

3. Place 1 ounce Natural Indigo powder (if you are working with hard chunk indigo it will have to be ground down first) into a suitable container.

4. Add just enough hot water until you get a paste – preferably lump free (I use a dedicated wide mouth pint jar for this solution.

5. Add soda ash or lye to the vat water - NEVER add water to your soda ash or lye ALWAYS add the soda ash or lye to the water!!!

6. Slowly add the indigo paste to the vat solution

7. Stir to dissolve NOTE this may take quite a bit of stirring, heating the vat at this point also helps with dissolving the paste faster.

8. Next add thiox to the vat solution stir very little so as to avoid adding Oxygen to the vat.

9. DO NOT BOIL YOUR VAT as this will cause bubble formation and will introduce Oxygen into the vat.

10. REMOVE HEAT after 30 minutes

11. Cover vat and allow to sit until reduction is complete.

12. Reduction is complete when your vat turns a yellow to yellowish pea green color.

13. If your vat is still blue after 24 hours then you have too much Oxygen in your vat add thiox to the vat in small increments, a few grains of thiox at a time, to further reduce the vat.

14. If you reduce the vat too far then gently stir the vat with one or two swirls of the spoon and allow to sit for 30 minutes.

15. You will need to test the pH of the vat to see if the pH is correct

16. pH should be 10.0 – 11.5
· cottons 11.0-11.5
· wool and silk 10.5-11.0 preferably closer to 10.5

17. Adjust pH by adding small amounts, half teaspoon at a time, of soda ash to your vat, even is you created a lye vat do NOT add more lye to the vat at this point.