How hair dye is made

Permanent hair color is a two-part kit, because the dye only forms inside the hair when the two halves meet.

stations: 5
things upstream: 44
raw sources: 12
steps from the ground: 9

The short version

Permanent hair dye is sold as two components. One is a colorant cream with ammonia, and the other is a developer, an oxidizing agent. Mixed on the head, the ammonia opens the hair's cuticle and the oxidizer lets the colorants form inside the cortex. Semi-permanent dyes skip both and only wedge under the cuticle.

Prepare the colorants

Dye intermediates such as p-phenylenediamine are made by chemical routes in a plant. They are the colorless building blocks that develop color on the hair.
Blend the colorant cream

A jacketed stainless steel vessel is charged with water and a thickening polymer and heated. Antioxidants and then the dye intermediates are dissolved one at a time, and the batch is cooled before the surfactant and ammonia go in.

Goes in
Water Ammonia
Make the developer

The developer is a separate lotion of hydrogen peroxide, mixed in its own vessel. That vessel is first soaked in peroxide solution for 24 hours to passivate the steel, so the metal will not break down the oxidizer.

Goes in
Water Hydrogen peroxide
Fill and pair the bottles

The colorant tubes and developer bottles are filled separately, so nothing reacts until the customer mixes them.

Goes in
Plastic bottle
Box the kit

Both parts are boxed together with instructions and gloves.

Goes in
Cardboard

End of the lineHair dye

Worth repeating

Assyrian herbals dating to 2177 BCE hold some of the oldest recorded recipes for hair dye.
Semi-permanent hair color survives only 4 to 8 shampoos, while demi-permanent lasts for about 20 to 28.