The short answer: colour-safe shampoo is shampoo that gives your dye the fewest chances to leave the hair, and the evidence says that depends mostly on how often you wash, how damaged the hair is and which shade you wear. Oxidative hair dye fades mainly because it dissolves in water, so each wash takes a little. A gentle cleanser, a conditioner every time and fewer washes slow that. No shampoo has been shown to stop it. Evera shampoos use a gentle, coconut-derived cleanser (sodium coco-sulfate), which is a sulfate, and we have no colour-retention test of our own.
Colour-safe shampoo: what the data says
Why the colour leaves at all
A 2009 paper in the Journal of Cosmetic Science (Zhou and colleagues, volume 60, issue 2, pages 217 to 238) opens with the plain fact that fading of oxidative colour from daily shampooing “occurs primarily through hair dye solubility in water”. The authors varied the surfactant, the pH and the type of hair. Three findings matter for anyone choosing a shampoo:
- Water does the work, and surfactants help it. The paper says most dyes used on hair are water soluble, and that the surfactants in shampoo and conditioner wet the hair and bring moisture into the shaft, which helps dye molecules leave with the water.
- Red goes first. Fading is especially pronounced with red dye, which is more water soluble and is removed to a greater extent during washes.
- Damage speeds it up. Bleached hair fades much faster than non-bleached hair, because damaged hair has lost protective surface lipid (the F-layer) and has larger pores on its cuticle cells.
What changes the speed
- Washing outweighs sunlight. The same paper reports earlier work finding that washing is the most significant factor in removing colour, with UV exposure significant only after 90 hours of intense irradiation. A 2005 Journal of Cosmetic Science study (Locke and Jachowicz) found fading was greatest when coloured hair was both irradiated and shampooed, and that coloured white and bleached hair changed much more than coloured brown hair.
- pH. The 2009 paper found that hair dye dissolves in water much faster at a higher pH than at a lower pH, because higher pH swells the cuticle and lets more dye out.
- Surfactant and time in contact. In a one-hour soak of dyed hair, the anionic surfactant SLES raised dye dissolution by 47% and the cationic surfactant CETAC by 127%. A one-hour soak is a stress test, not a shampoo, but contact time clearly counts.
- The dye itself. A 2015 review in the International Journal of Trichology (Gavazzoni Dias) says demi-permanent colour fades after 10 to 15 shampoos, or even earlier.
What has been shown to slow fading, and what has not
The Zhou authors, who worked at a polymer supplier, then looked for a fix. Their best result was a hydrophobically modified cationic polymer, Polyquaternium-55, which in a colour-protection regimen gave up to 50% colour protection in tests on human-hair tresses and mannequin heads and outperformed the commercial colour-claim products they tested. None of the Evera products in this article list Polyquaternium-55.
A trade-press summary in Personal Care Magazine cites earlier work (Kiplinger and colleagues) saying that milder anionic surfactants, or added amphoteric co-surfactants, can reduce the rate of fading during shampooing. It also reports a test on red-dyed hair in which an amphoteric co-surfactant retained colour better than a nonionic one, and a silicone-based conditioning additive retained colour better than the cationic polymers chosen. We say that last point plainly: Evera shampoos, masks and gloss are silicone-free, so we cannot borrow that result.
On sulfates, the evidence is thinner than the labels suggest. The 2015 Trichology review says there are no published analyses of the cleansing power or hair-shaft effects of sulfateless shampoos. Removing sulfates may suit you, but it has not been shown to protect colour.
What a colour-safe label can legally rest on
The ASA and CAP say marketers need to hold evidence for all objective claims, and that claims a product can protect against damage are likely to be acceptable if evidence is held. The common criteria for cosmetic claims (Regulation 655/2013, as published on legislation.gov.uk) require claims, explicit or implicit, to be supported by adequate and verifiable evidence, and say that claims extrapolating an ingredient’s properties need evidence of an effective concentration. So “colour-safe” means something only if the brand can show you the test. It is also why we do not say a henna extract in a rinse-off shampoo tints hair.
Where Evera honestly stands
Supherbal Shampoo No.3, Supherbal Shampoo No.4 and Supherbal Shampoo No.5 all list water first and sodium coco-sulfate second. The Cosmetic Ingredient Review panel assessed sodium coco-sulfate with 14 related alkyl sulfates, used as surfactants at 0.1% to 29% mainly in soaps and shampoos, and judged them safe in the practices of use and concentration described. It is still a sulfate. Around it sit cocamidopropyl betaine, decyl glucoside, coco-glucoside, coco-betaine and sodium sunflowerseedamphoacetate, the milder half of the system. For the full argument on this one ingredient, read our guide to sodium coco-sulfate.
What we cannot tell you: how long your colour will last, whether our shampoos slow fading more than another gentle shampoo, or their pH. The lists show citric and lactic acid but not a final pH, so we make no pH claim. Evera is made in Italy and used every day in four London salons (GA Salons), but that describes use, not a laboratory result.
Who it suits: people who want a plant-led, silicone-free, paraben-free, vegan shampoo they can wash with often, and who would rather see the ingredients than a claim. Who it does not suit: anyone avoiding all sulfates, and anyone who wants proof of colour retention, which we do not have.
How to choose a shampoo for colour-treated hair
- Ask what the claim rests on. A test, a dye, a number of washes.
- Read the first five ingredients. They show what cleans and what cushions.
- Match the product to your hair’s condition. Bleached and porous hair loses dye fastest, so it needs the gentlest routine and a conditioner every time.
- Judge it over several washes. One wash tells you about feel, not colour.
- Treat shade-specific lines as a preference. We have no measured tone change for any of ours.
Evera picks for colour-treated hair
What each label lists, prices from the live product pages:
| Product | Size | Price | Per 100 ml | Plant colour-line extracts on the label |
|---|---|---|---|---|
| Supherbal Shampoo No.3 (Red) | 250 ml | £38 | £15.20 | Henna leaf, hibiscus, goji |
| Supherbal Shampoo No.4 (Blonde) | 250 ml | £38 | £15.20 | Rhubarb stem, calendula, hops |
| Supherbal Shampoo No.5 (Dark) | 250 ml | £38 | £15.20 | Indigofera tinctoria leaf, black currant, licorice |
| Supherbal Mask N3 (Red) | 180 ml | £38 | £21.11 | Henna leaf, madder root powder, hibiscus, goji |
| Supherbal Mask No.4 (Blonde) | 180 ml | £35 | £19.44 | Rhubarb stem, calendula, hops |
| Supherbal Mask No.5 (Dark) | 180 ml | £35 | £19.44 | Indigofera tinctoria leaf, black currant, licorice, tea leaf powder |
| Liquid Gloss Treatment No.0 | 125 ml | £28 | £22.40 | Cetrimonium chloride, behentrimonium chloride, hydrolyzed soy and wheat proteins, amino acids |
All three masks list hydrolysed rice protein, rice bran oil and shea butter. A shampoo and its matching mask come to £73 for the blonde or dark pair and £76 for the red pair before any code. Browse them in the shampoo for coloured hair collection.
One honest note on the gloss: the CETAC in the soak test above is cetrimonium chloride, which Liquid Gloss also lists. A five-minute treatment is a different exposure from a one-hour soak, but we cannot say it makes no difference to colour, so we sell the gloss for shine and detangling, not as a colour-protect product.
If you wash often and want one plain pair rather than a shade line, The Daily Duo N1 is Frequent Use Shampoo N1 and Frequent Use Conditioner N1 for £63 instead of £70. It is not colour-specific and we make no colour claim for it, but it is a gentle everyday pair that puts conditioner into every wash.
Use code EVERA10 for 10% off a first order, or ROUTINE10 for 10% off when two or more items are in the cart. UK delivery is free on every order. Unopened, sealed products can be returned within 30 days of delivery under the Evera guarantee, and faulty or wrong items are refunded or replaced.
A word on henna: the 2015 Trichology review notes a few reports of allergic contact dermatitis to it, and NHS 111 Wales advises a patch test before permanent or semi-permanent hair dye. Our henna products are rinse-off and are not dyes, but if you are prone to reactions, test a small area first.
A wash routine that gives colour the best chance
These steps follow from the mechanism, that dye leaves in water and leaves faster from damaged hair. They are general craft, not tested protocols, and we give no temperatures or day counts because we have no source for them.
- Wash less when you can. Every wash you skip is one less opportunity for dye to dissolve.
- Keep shampoo on the scalp. Work it in at the roots and let the suds run through the lengths, rather than scrubbing the ends.
- Condition every time. The lengths and ends have been through the most washing and colouring.
- Do not leave products on longer than needed. Contact time counts, as the soak result shows.
- Cover up in strong sun. The 2005 study found fading greatest when light exposure and washing combine.
For a wider look at natural cleansers, see our guide to natural shampoo for coloured hair.
“I was a bit worried at first that it might stain my towel because it has real ingredients like henna, but it didn’t at all. It does feel a little bit like you’re doing a colour treatment in the shower, and it can leave a bit of residue in the bath, but nothing scary and no staining.”
Andy, on Supherbal Mask N3 (five stars)
Frequently asked questions
What does colour-safe shampoo actually mean?
Nothing fixed. In the sources we read, there is no standard test a shampoo must pass to be called colour-safe. UK advertising guidance says objective claims need evidence behind them, and the common criteria for cosmetic claims say the evidence must be adequate and verifiable. So treat the phrase as a question to the brand: what was tested, on which dye, over how many washes?
Does a colour-safe shampoo stop dye fading?
No shampoo stops it. Oxidative dye fades mainly because it dissolves in water, so every wash and rinse takes a little. One laboratory study reported up to 50% colour protection from a specific cationic polymer, but that is a tested ingredient, not a label, and none of the Evera products in this article list it. We have no colour-retention test of our own, so we do not claim Evera slows fading.
Is sodium coco-sulfate all right for coloured hair?
It is a sulfate, so if you want none at all, Evera shampoos are not for you. The Cosmetic Ingredient Review panel judged it safe in the practices of use and concentration described. A 2015 review found no published analysis of the cleansing power or hair-shaft effects of sulfateless shampoos, so there is no evidence either way on colour. Ours pair it with milder betaine and glucoside co-surfactants.
Will a shampoo with henna, indigo or rhubarb change my hair colour?
We cannot show that it will. Supherbal Shampoo No.3 lists henna leaf extract, Supherbal Shampoo No.5 lists indigofera tinctoria leaf extract and Supherbal Shampoo No.4 lists rhubarb stem extract, each as the third ingredient after water and sodium coco-sulfate. They are cleansers formulated with plant extracts, and we have no measurements of tone change.
How often should I wash dyed hair?
As seldom as your scalp is comfortable with. The research ties colour loss to washing, and a 2015 review says demi-permanent colour fades after 10 to 15 shampoos, or even earlier. We have no study that gives a number of days between washes, so we will not invent one.
Sources
- Zhou Y, Foltis L, Moore DJ, Rigoletto R. Protection of oxidative hair color fading from shampoo washing by hydrophobically modified cationic polymers. J Cosmet Sci 2009;60(2):217-38 (PubMed)
- Society of Cosmetic Chemists library, same paper, introduction (washing and UV)
- Society of Cosmetic Chemists library, same paper (dye solubility, red dye, bleached hair)
- Society of Cosmetic Chemists library, same paper (surfactant and pH tests)
- Locke B, Jachowicz J. Fading of artificial hair color and its prevention by photofilters. J Cosmet Sci 2005;56(6)
- Gavazzoni Dias MFR. Hair cosmetics: an overview. Int J Trichology 2015
- Personal Care Magazine: effects of co-surfactant and conditioning agent on colour
- Cosmetic Ingredient Review: sodium cetearyl sulfate and related alkyl sulfates. Int J Toxicol 2010
- ASA and CAP advice: hair care claims
- Commission Regulation (EU) No 655/2013: common criteria for cosmetic claims (legislation.gov.uk)
- NHS 111 Wales: hair dye reactions
Evera ingredient lists, sizes and prices come from the live product pages.
