Updated 29 August 2026. Test carried out July 2024. The photographs are unchanged; what we have added is the name problem underneath them, and an account of what this test does not show.
People ask us this before they buy, and it is exactly the right question. A powder called colorless henna, sold by a hair colour company, is fair to be suspicious of. So we dyed some hair with it and photographed what happened.
The short answer: on brown hair, nothing. On gray hair, so little that we had to look twice. The long answer is below, along with the part where we tell you what this test does not prove.
First, a name problem
Two different plants are sold as colorless henna, and we use both.
- Cassia obovata — the single-herb powder we sell on its own, as a hair mask. This is what was tested below.
- Cassia auriculata — the colorless henna inside our hair colours, where it takes up room in the blend so a light shade is possible.
Same genus, same use, a different species. Supply across the industry shifted from one to the other between roughly 2016 and 2020, and most brands never mentioned it. We print the botanical name on both.
Why did the market change?
Nobody announced it, and we have not found an authoritative account of why it happened. What follows is our reading of it, not a history we can cite. We would rather set the reasoning out and let you weigh it.
The first part is simply where the plants grow. Cassia auriculata is an Indian crop. It grows across the dry zones of the south and west, it is the state flower of Telangana, and its bark was one of the country's principal tanning materials for the better part of a century — which is why English calls it tanner's cassia. There was already a harvest, a supply chain and a price for it. Cassia obovata, in the hair trade, has been associated with North Africa and the Middle East. India is where henna and herbal powders are milled and exported from. The local plant had the advantage.
The second part is the one we think actually decided it, and it is slightly counterintuitive. C. auriculata colours even less than C. obovata does. Catherine Cartwright-Jones, whose research on henna is the most detailed we know of, states it plainly: auriculata does not stain hair as well, and most people get no colour from it at all, even on pale hair. Indian bulk suppliers now list it exactly that way — neutral henna that does not impart colour.
For a product sold as colorless henna, colouring less is not a downgrade. It is the product doing its job better. The faint golden cast on white and platinum hair — the one thing we ask people to strand test for — is the most common complaint about C. obovata. A plant that is locally grown, already in commerce, and more faithful to the name on the pouch is an easy substitution for a supplier to make.
Our own split follows the same logic from the other direction. C. auriculata goes into the hair colours, where it has to take up room without contributing anything of its own. C. obovata is what we sell on its own, where a little warmth on very pale hair is a known characteristic we disclose rather than a fault we hide. Two plants, two jobs, and we print which is which.
So everything below describes Cassia obovata. It is not a test of what is in our hair colours, and we would rather say so than let a photograph do work it was not set up to do.
The test
Two hair samples, one gray and one brown. One hundred per cent organic Cassia obovata leaf powder, nothing added. One hour on the hair — the middle of the 30 to 60 minutes we recommend.
Mixing the paste
The powder is stirred into water. It does not dissolve easily, and that is worth knowing before you try it at home — milled leaf needs working at until it is smooth, and lumps will not spread.
Applying it
The paste goes onto both hair samples and stays there for an hour.
Results
Brown hair: no visible change. Not a subtle one — none.
Gray hair: very slightly deeper, and difficult to see. Under magnification there is something there. Side by side at arm's length, most people would not pick it out.
That is the whole result, and it is the reason the powder is called colorless henna in the first place.
Why the brown sample showed nothing
This is not just what happened in our kitchen. It matches the one published study we have found that followed this plant onto hair fibres rather than testing its compounds in isolation.
Forestier, publishing in 1981, tracked how much the hair took up over time. On bleached hair, uptake was quick. On light and white hair it happened, but less. On dark hair he recorded none at all. Hair that had been pre-treated with peroxide took up more than untreated hair, which he read as the plant's components binding to cysteic acid — a group that oxidation creates in keratin, and that undamaged dark hair has very little of.
So the brown sample did not resist the dye. There was very little in it for the dye to attach to.
What this test does not show
We would rather list this than have you find it out yourself.
- We did not test the one case where we tell people to be careful. On white, platinum or very pale blonde hair, a long application can leave a faint golden or straw-toned cast. Forestier's fastest uptake was on bleached hair. Our samples were gray and brown — neither of them the case in question. If your hair is in that range, strand test, and start at 20 minutes rather than 60.
- One hour, one batch, one pair of samples. Not a controlled trial. Plant material varies between harvests, and hair varies between heads.
- Hair swatches are not a head of hair. Porosity, previous colour and water hardness all move results, and none of them were varied here.
- Colorless is not quite the right word, and we know it. The principal compound in C. obovata leaf is chrysophanol, which PubChem lists as a golden yellow solid. It is a dye. It is simply a weak one, and at these concentrations and contact times most people see nothing. That is why we say near-neutral rather than colorless.
If you are buying the single-herb powder
This test is the reason we sell it as a hair mask rather than a colour. On brown, black, red or gray hair you can use it without expecting your colour to move. It carries no added protein at all, which is the useful fact for anyone whose hair has gone stiff on conventional protein masks — that is a statement about the ingredient list rather than a promise about outcomes.
We are not claiming it treats dandruff, flaking, scalp inflammation or any other condition. In the United States a cosmetic may not make that claim, and we have not run the studies that would support one.
If you are buying a hair colour
The colorless henna in our shades is the other plant — Cassia auriculata — and it is doing a different job. There it is not a treatment. It takes up room in the pouch so that the herbs which do colour are working on a smaller share of the powder, which is how a blonde or a light brown exists at all without bleach.
Thirteen of our twenty-four shades contain it, and on each product page you can see exactly where it sits on the ingredient list. Where it sits first, the shade is light. That is the whole mechanism, and it is printed on the pouch.
One thing worth timing, whichever you have. Do not use the single-herb colorless henna in the 72 hours after a plant colour. Henna and indigo keep developing for up to three days, and an hour of a wet mask inside that window can carry some of the result away with it.
References
Forestier JP. A cosmetic senna, Cassia obovata: 'neutral henna'. Int J Cosmet Sci. 1981 Oct;3(5):211–26. doi: 10.1111/j.1467-2494.1981.tb00284.x. PMID: 19469940.
Note the species. Forestier's work is on C. obovata. We have not found the equivalent for C. auriculata, which is why we do not cite it on our shade pages.
Cartwright-Jones C. Henna for Hair / Ancient Sunrise technical writing on cassia, on the difference between Cassia obovata and Cassia auriculata. mehandi.com
Chrysophanol, PubChem CID 10208. pubchem.ncbi.nlm.nih.gov/compound/10208
Radico Organic Colorless Henna Leaf Powder is a cosmetic product for external use on hair and scalp. It is not intended to diagnose, treat, cure or prevent any condition. Patch test on the inner forearm 48 hours before a full application, and stop use if irritation develops.