What Henna Actually Does to Hair, for Brands Building a Colour Line

Women have coloured their hair with henna for a very long time, and most of them did not switch to a box dye because henna stopped working. They switched because henna was inconvenient. Then, somewhere around the point where scalp irritation and chemical smell stopped being acceptable, a lot of them switched back.

That swing is the market your brand is selling into. This is what henna actually does for hair, written for the person deciding whether to build a product line around it.

What henna does to hair, physically

Henna is the dried, milled leaf of Lawsonia inermis. The molecule that matters is lawsone. Lawsone binds to keratin, which is the protein your hair is made of. It does not lift the cuticle and deposit pigment inside the shaft the way an oxidative dye does. It binds to the outside.

Two consequences follow, and both are selling points.

The colour is a stain, not a replacement. Henna cannot lighten hair. It goes over what is already there, so the result depends on the starting shade, which is why the same batch gives a coppery red on light brown hair and a subtle warm shift on dark hair. Brands that explain this up front get far fewer complaints than brands that print one swatch on the pack.

Because the lawsone sits on the cuticle, it also fills in. Hair that has been chemically processed feels rougher because the cuticle is lifted and chipped. A henna coat smooths that surface. Customers describe it as thicker, glossier hair. What they are feeling is a more even cuticle reflecting light more consistently.

The strength number your formulator needs

Lawsone content is the only figure that predicts how a henna will perform, and it is the one most suppliers do not print.

Ours is assayed by HPLC and runs at 2.5% or 3.0% and above depending on grade. That range is the difference between a wash that fades in three weeks and one that holds. If you are building a colour line, ask every supplier you talk to for the lawsone figure on the actual lot they are quoting, not a specification sheet written once and reused for five years.

The second number is sieve size. Body Art Quality henna is milled to 100 mesh. That fineness is why BAQ paste goes on smooth and rinses out cleanly instead of leaving grit at the roots. For a hair product it is the difference between a customer who reorders and one who does not.

PPD is the thing your customer is actually worried about

Paraphenylenediamine is the compound behind most reported reactions to hair dye, and it is why a whole segment of buyers left conventional colour in the first place. It also turns up in cheap henna, added to force a black result, which is the practice that gave “compound henna” its bad name.

We test for it by GC-MS and it is absent. That is a line worth putting on your pack, because the customer searching for henna has usually already had a bad experience and is looking for a reason to trust someone.

Where henna stops, and indigo starts

Henna on its own does not produce brown or black. It produces red. Every genuinely natural dark shade on the market is henna followed by indigo, applied in two steps.

Anyone selling you a single-step natural black is selling you something with an additive in it. That is worth knowing before you build a range around a supplier’s claim. We cover the two-step method properly in the indigo sourcing guide.

What this means for a product line

Three things decide whether a henna line works commercially.

Crop freshness. Lawsone degrades. Henna from an old crop dyes weakly no matter what the label says, and shelf life is two to three years from harvest, not from the day it was packed for you. Ask when the crop was harvested.

Consistency between orders. Your customer notices when batch four is lighter than batch one. This is a supplier problem, not a formulation problem, and it is solved by buying against an assay rather than against a photo.

Origin. Sojat in Rajasthan grows the majority of the world’s commercial henna. The climate is the reason: hot, dry, and poor soil, which stresses the plant into producing more lawsone. Henna from wetter regions grows greener leaves and dyes worse.

Getting a sample

We mill henna in Sojat, supply from 50 kg, and pack in plain or custom printed bags for private label. A COA ships with every lot covering lawsone content, sieve size and PPD.

Before you order anything, take a free sample and put it on hair. A specification sheet tells you what a supplier intends. A strand test tells you what they actually shipped.