Five Pigments.
Four Ways of Staying.

Henna

Lawsonia inermis

Bonds

This is the only one of the five where the pigment becomes part of the fibre. That is why a henna shade does not rinse out. It wears off, at the rate the outer layers of the hair wear off, which is slow.

One honesty about the bond, because our other pages lean on it. Not every lawsone molecule that lands on the hair makes that bond. Some sits loosely, held by weaker attractions, and that loosely held fraction is what an alkaline rinse can lift back out. The bonded fraction stays. So “henna is permanent” and “alkaline water fades henna” are both true, about different molecules on the same strand.

Indigo

Indigofera tinctoria

Forms in place

Indigo never bonds to anything. It is held the way a pebble is held by a jar with a narrow neck: it got in as something smaller and became something larger. This is vat-dye chemistry — the same route that colours denim, where the dye is also formed inside the fibre rather than attached to it.

A side route matters too. Some indoxyl oxidises a step further into isatin, and isatin joining with indoxyl gives indirubin, which is red-violet rather than blue. That reaction is slower, so it arrives late — part of why the tone keeps moving for days.

Everything strange about indigo follows from this. It is green at the rinse because the reaction is halfway through. It keeps developing for two to three days because the reaction runs on. It stops if you blow-dry because the reaction needs water. It fades sooner than henna because nothing is holding it but the fibre's shape. And it holds better over henna — which we can see, but cannot yet explain in terms of mechanism.

Manjistha

Rubia cordifolia

Sits on the surface

So manjistha's red rests on the hair rather than joining it. It warms and deepens a shade for as long as it stays, and it washes down gradually. On dark hair very little of it is visible in any case; it does its work under the henna.

We are not going to dress this up. How much of manjistha's pigment actually ends up on a hair fibre, and how long it lasts there, has not been measured by anyone we can find. What we can tell you is what is in the root and how this class of dye behaves on other fibres.

Hibiscus

Hibiscus rosa-sinensis

Sits on the surface

Cyanidin reads magenta — a red with blue in it. That is what makes hibiscus a cool red beside henna's warm one, and why it sits in shades that need the warmth held in check.

The pH behaviour is not a footnote. Amla, which is in nearly every one of our shades, keeps the paste on the acid side — which is the side hibiscus reads red on. Take the acid away and the same pigment drifts purple.

How well is this known? The pigment class has been measured on hair, in a study of blackcurrant anthocyanins. It found adsorption rather than bonding, build-up through the pigments stacking on each other, and blue tones stabilised by the hair itself. Hibiscus is the same class, with a different sugar attached. Hibiscus specifically has not been measured, and the blackcurrant authors hold commercial interests in that work, which is worth knowing when you read it.

We have watched the pH behaviour happen, though we have not measured it. Hibiscus mixed with lemon juice and left an hour on a white swatch comes out red-purple; the same powder mixed with plain water comes out blue-purple. That is one pigment in two arrangements, and it is the clearest demonstration we have of why amla’s acidity matters in a blend. What it is not is a measurement: we did not put a meter in either paste, and we did not test how long either colour lasted. See both swatches →

Turmeric

Curcuma longa

Stains

Turmeric is the pigment in exactly one of our shades, Sun Blonde, and it behaves like nothing else in the range. No green stage, no 72-hour wait, no rule about air-drying. The trade-off is at the other end: curcumin breaks down in light, and it fades faster in sunlight than any pigment we work with. No formulation gets around that.

It is also a pH indicator — yellow in acid and neutral conditions, red-brown once the pH climbs past about eight. Amla, in the same pouch, keeps it on the yellow side.

Colourless henna

Cassia auriculata in the colours · Cassia obovata in the care powder

Barely colours

This is dilution, not chemistry, and it is what makes a blonde possible at all. A pale shade needs less pigment per gram, and the honest way to get there is a plant that barely tints rather than a filler that is not a plant.

The other Cassia — C. obovata, which we sell on its own — has one old study behind it: on bleached hair its components bound to cysteic acid, a group that oxidation creates in keratin, and on dark hair they did not bind at all. That study does not transfer to C. auriculata, and we do not use it as if it did.