Our Own Test · 1, 2 and 3 Hours
Does Leaving It On Longer
Change the Colour?
It is one of the questions we are asked most. The honest answer is: it depends on the shade. We put three of our colours on grey hair for one, two and three hours — the same bowl of paste for each shade — and photographed all nine swatches together for three days.
The second finding changed our own colour swatch for Darkest Ash Blonde. If you are choosing an ash shade for grey hair, it is worth reading before you buy.
How We Tested
One Bowl Per Shade.
Only the Clock Changed.
Each shade was mixed once and the same paste went on all three of its swatches. The only thing that differed between them was how long the paste stayed on — so any difference in the result comes from the time.
The three shades
Two from our henna-free group, where indigo does all the colouring, and one that leads with indigo and henna together.
Wheat Blonde
Indigo, no henna · label 120–180 min
Amla, indigo, colourless henna (Cassia auriculata), bhringraj, brahmi.
Darkest Ash Blonde
Indigo, no henna · label 120–180 min
Amla, indigo, brahmi, bhringraj. Indigo is the only herb with colour.
Soft Black
Henna and indigo · label 60–90 min
Five herbs, led by indigo and henna. pH measured with the same mix in our drying test.
One swatch per shade and time. Colour values are measured from the photographs (CIELAB), not with a lab instrument — good for comparing swatches photographed together, less precise for dark shades. pH readings with a food pH meter, one reading each.
The Results
Every Swatch, Every Day.
Pick a shade. Rows are the time on the hair, columns are the time since rinsing. Each strip is cut from the same spot of the same swatch in each photograph.
Values are the median colour of each strip, measured from the photographs after evening out the lighting against the undyed swatch. ⚠ Darkest Ash Blonde, one hour, at 72 hours reads much lighter than the day before; no other swatch jumped like that, so we treat it as a difference in how that swatch lay in the photo rather than a change in colour.
Finding 1 · Depth
Extra Time Matters Most
Where Indigo Works Alone.
The two henna-free shades kept getting darker with more time on the hair. Soft Black, which has henna and indigo working together, was already most of the way there after one hour.
Why the henna-free shades need the time
In Wheat Blonde and Darkest Ash Blonde, indigo is the only herb that colours. Indigo is the slower of the two dye plants, so the clock decides how much of it reaches the hair. That is why their labels ask for two to three hours rather than one.
Wheat Blonde stepped down evenly: each extra hour made a visible difference. Darkest Ash Blonde behaved differently — two hours was barely darker than one, and the third hour did most of the work.
Why Soft Black changed so little
Soft Black leads with indigo and henna, and it is a dense blend — there is a lot of pigment on the hair within the first hour. Three hours made it slightly deeper, but not a different shade. One hour, the start of its label range, did most of the work.
What we can't tell you yet. This is one swatch per shade and time, on grey hair. We don't know why Darkest Ash Blonde gained so little in its second hour, and natural hair that already has colour will not show differences as clearly as grey does. Our application guide gives the time range for every shade.
Finding 2 · Tone
Darkest Ash Blonde Turned
Mauve-Taupe Over Two Days.
At 90 minutes all three Darkest Ash swatches were a cool greige. Over the next two days they moved steadily towards mauve, then stopped. It happened at one hour, two hours and three — and it happened even though they were dried slowly in a towel.
Redness of Darkest Ash Blonde, by day
a* from the photographs. Around 0 is neutral; higher is pinker. The rise stops between 48 and 72 hours.
| Time on | 90 min | 24 h | 48 h | 72 h |
|---|---|---|---|---|
| 1 hour | −0.5 | +3.8 | +5.8 | +5.5 |
| 2 hours | −0.6 | +3.9 | +5.8 | +5.6 |
| 3 hours | +0.7 | +6.1 | +7.4 | +7.3 |
At the same time the yellow drained out: yellowness b* fell from about 8–11 to about 2–4. Less yellow plus more red reads as mauve. For comparison, Wheat Blonde ended at +0.5 to +2.3 and Soft Black at +1.6 to +2.7.
It isn’t the time, and it isn’t the drying
Time: one, two and three hours all ended within about two points of each other. Longer time made the swatch darker (Finding 1), not noticeably more mauve.
Drying: in an earlier test we left Darkest Ash Blonde on for one hour and dried three swatches three ways. At 72 hours all three were mauve — the towel-wrapped one (+6.8) as much as the one left to dry on its own (+6.5), and more than the fan-dried one (+4.5).
Where the mauve comes from
Darkest Ash Blonde has one colouring herb: indigo. As indigo develops on the hair it forms blue, and alongside it a little red-violet. In this blend there is nothing to balance the red-violet — no henna orange, no yellow from colourless henna — so on grey hair you see it. How indigo develops →
Darkest Ash Blonde
Amla, indigo, brahmi, bhringraj. Indigo is the only pigment, so its red-violet shows on grey.
Wheat Blonde
Also henna-free, but with colourless henna third. Its faint yellow sits opposite violet — our best explanation for why the result stayed beige.
Soft Black
Henna’s orange and a lot of depth absorb a small red-violet shift. It is there in the numbers, not to the eye.
What we changed because of this
Our old Darkest Ash Blonde swatch showed a dark olive brown. That isn’t what this shade does on grey hair. We have replaced it with the colour of the three-hour swatch at two to three days — measured, not picked by eye.
On natural hair that is darker than grey, the result is deeper and the mauve much less visible. If you are covering a lot of grey and want a neutral ash, this is worth knowing before you choose.
Still open. Our indigo-only test, mixed with water at pH 6.28, stayed close to neutral when towel-dried. Darkest Ash Blonde, at pH 4.59 with amla first, turned mauve even when towel-dried. Whether the acidity is part of the reason, we don’t know yet — it is the next thing we are testing, and we will add the result here.
What It Means for You
How Long to Leave It On,
Shade by Shade.
Based on this test only — one swatch per shade and time, on grey hair. Your own hair, and how much grey you have, will change how strong each effect looks.
Wheat Blonde
Label: 120–180 minutes
- Time is your depth control. Each hour gave a visibly darker beige.
- Stopping at one hour leaves it much lighter than the shade is built to be.
- The tone stayed beige — no mauve on grey.
Darkest Ash Blonde
Label: 120–180 minutes
- Give it the full three hours if you want depth — most of the extra darkness came in the third hour.
- On grey, expect mauve-taupe, not a flat ash. It develops over two days and settles; shorter time doesn’t avoid it.
- Judge the colour on day two or three, not at the rinse.
Soft Black
Label: 60–90 minutes
- One hour did most of the work. Longer gave a slightly deeper black, not a different shade.
- How you dry it matters more than the extra time — see our drying test.
For every shade
Keep the paste moist. Wrap it. Paste that dries on the hair stops working, whatever the clock says.
No dryer after rinsing. Wrap in a towel and let it dry slowly.
Wait two to three days before judging. Every swatch here was still changing on day one.
Start within the label range. This test only tells you what happens inside it, not beyond three hours.
Testing now
Dark Ash, Ash and Light Ash Blonde
The same test on the rest of our ash shades. We want to know whether they turn mauve too, and we will update their colour swatches from the results.
Running for six weeks
How long the colour lasts
These nine swatches are now washed once a day with our shampoo bar and photographed every week. The results will be added to this page.
How to apply, step by step · Our drying test · First order? The same shade again, a different shade, or a refund