By Rehues Editorial Team | April 2026
Your shampoo is the single product you use most frequently on your hair. If you have colour-treated hair, it is also the product most capable of either protecting your investment or steadily destroying it. The wrong shampoo can strip weeks of salon colour in a matter of days. The right one extends your vibrancy, strengthens your strands, and makes your colour look as good in week six as it did on day one. This guide covers what specifically harms coloured hair, what ingredients to actively seek out, and why the Rehues Colour Lock Shampoo is engineered for exactly the conditions Singapore's climate creates.
What Actually Damages Coloured Hair
Understanding what harms your colour makes it much easier to understand what you're looking for in a protective shampoo. The threats are well-established in cosmetic chemistry.
Sulphates are the most significant culprit. Sodium Lauryl Sulphate (SLS) and Sodium Laureth Sulphate (SLES) are the most commonly used surfactants in commercial shampoos because they create a rich lather and are inexpensive to produce. The problem is that they are highly effective at removing not just dirt and oil but also the dye molecules sitting in and on your hair shaft. Every wash with a sulphate-heavy formula effectively pulls colour out of your hair along with the day's build-up. The more frequently you wash — and in Singapore, daily or near-daily washing is the norm given the heat and humidity — the faster your colour fades.
Parabens are preservatives used to extend shelf life in cosmetic products. Whilst the debate around their broader health implications continues, their relevance for colour-treated hair is more straightforward: they can disrupt the structural integrity of colour-treated hair over time and have been associated with scalp irritation, which is already a concern post-colouring.
High-pH formulas open the hair cuticle rather than keeping it sealed. The cuticle is the outermost layer of the hair shaft and functions as a kind of armour — when it's flat and sealed, it locks colour in and keeps moisture in. When it's forced open by alkaline formulas, both colour and moisture escape. Most colour-safe shampoos are formulated at a slightly acidic pH (4.5–5.5) to keep the cuticle closed and colour sealed inside.
Heat and UV exposure compound the damage done by harsh shampoos. Singapore's year-round UV index is among the highest in the world, and UV radiation directly degrades dye molecules — warm pigments tend to survive longer than cool ones, which is why bleached, ash, and cool-toned colour drifts brassy so quickly.
What to Look for in a Colour-Safe Shampoo
A genuinely colour-protective shampoo needs to do more than simply omit sulphates. Look for formulas that actively repair and strengthen alongside protecting.
Keratin and bond-repair ingredients matter because colouring — especially bleaching and highlighting — breaks the disulphide bonds that give hair its structural strength. A shampoo with a dedicated bond-repair complex helps reverse this damage with every wash rather than letting it accumulate.
Panthenol (Pro-Vitamin B5) penetrates the cortex of the hair shaft and binds to moisture from within, improving flexibility and reducing the brittleness that makes colour-treated hair prone to breakage. Hyaluronic acid, specifically in its sodium hyaluronate form (which has a smaller molecular weight and therefore deeper penetration), provides intense hydration to strands that have been depleted by chemical processing.
Soothing botanicals support scalp health, which is often overlooked in the conversation about colour care. A compromised scalp — one that's dry, irritated, or inflamed — affects hair growth and quality at the root.
Pigment-deposit technology for shade-matching means that rather than simply not removing colour, the shampoo actively replenishes tone during each wash. This is the difference between a shampoo that is merely colour-safe and one that is colour-enhancing.
Why Singapore Hair Needs Specific Attention
The generic advice you read on global beauty sites often underestimates Singapore's climate. The combination of high heat, persistent humidity above 80%, and intense UV exposure year-round creates conditions that accelerate colour fade significantly faster than in temperate climates.
Frequent washing intensifies the problem. In Singapore, many people wash their hair daily or every other day because of sweat and humidity — and every wash cycle removes some colour pigment. Hard water, which contains elevated levels of calcium and magnesium, also contributes by creating a mineral film on the hair that dulls colour and interferes with how conditioning ingredients work.
This means that a shampoo designed for colour-treated hair in Singapore needs to work harder on multiple fronts simultaneously: gentle cleansing, active colour protection, bond repair, and moisture retention — all in a single wash.
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Rehues Colour Lock Shampoo: What Makes It Different
The Rehues Colour Lock Shampoo was developed around two proprietary technologies that address the root causes of colour fade rather than simply minimising them.
The Colour Lock Blend™ is formulated to target tone fade directly and neutralise brassiness — the drift toward warm, yellow-orange tones that colour-treated hair experiences as dye molecules break down. Most shampoos merely slow this process; the Colour Lock Blend™ is engineered to counteract it actively.
The Bond Repair Complex rebuilds broken disulphide bonds within the hair shaft. Because bleaching and colouring both cause bond breakage, and because repeated washing in Singapore's climate further stresses already compromised strands, a shampoo that includes genuine bond repair technology is providing something that most colour-safe shampoos simply don't.
The supporting ingredient profile reinforces both technologies. Panthenol provides cortex-level moisture retention, Sodium Hyaluronate delivers deep hydration, Amodimethicone smooths the cuticle for improved shine and manageability, Sophora Angustifolia Root Extract soothes the scalp, and Glycerin maintains surface hydration. The cleanser is Cocamidopropyl Betaine — effective, gentle, and crucially, not a sulphate. There is no SLS, no SLES, and no parabens in the formula.
Shade-Matching for Your Colour
One of the most practical features of the Rehues range is that the Colour Lock Shampoo comes in four shades, each formulated with specific pigments to enhance and maintain different hair colours.
The Brown shade contains Basic Yellow 87 and Basic Red 51, which together produce warm toning to maintain the richness of brown, brunette, and warm-toned hair. The Blue shade contains Ext. Violet 2, which provides cool violet toning for bleached, blonde, highlighted, and silver hair — functioning similarly to a purple or toning shampoo. The Pink shade contains Basic Red 51 for colour deposit that refreshes and maintains pink-toned hair. The Grey shade combines Ext. Violet 2 with Basic Yellow 87 and Basic Red 51 to maintain the silver and grey tones of natural grey or intentionally silver-dyed hair.
Choosing the shade that matches your hair colour means you're not just washing — you're actively reinforcing your colour with every wash.
Pairing with the Collagen Elixir Spray
For complete daily colour protection, pairing the Colour Lock Shampoo with the Rehues Collagen Elixir Spray adds an additional layer of defence between washes. The spray is water-based with micro collagen peptides that penetrate the cuticle to fill weak spots along the hair shaft, form a protective film that locks in hydration and shine, and support elasticity to reduce brittleness and breakage.
Used after washing — or as a daily styling and finishing product — the Collagen Elixir Spray provides the kind of ongoing protein support that colour-treated hair, which is essentially pre-damaged by the colouring process, needs every day, not just on wash days.
Delivery, Subscriptions & Returns
Current Promotion
Rehues is currently running a Mother's Day Sale with up to 50% off sets and free SG shipping. Every Colour Lock Shampoo bundle includes a free Steam Hair Mask (worth $15.90) — a heat-activated treatment that is an ideal companion for maintaining colour-treated hair between salon visits.
Conclusion
The best shampoo for coloured hair in Singapore is not simply one that omits sulphates. It is one that actively repairs bond damage, deposits tone-matching pigments, restores moisture, and provides the consistent protection that Singapore's UV-heavy, high-humidity climate demands. The Rehues Colour Lock Shampoo delivers all of this through its Colour Lock Blend™, Bond Repair Complex, and carefully selected supporting ingredients — in four shade-matched formulas designed for different colour types. If you're serious about maintaining your colour between salon visits, it is the most complete option currently available.
Frequently Asked Questions
What ingredients in shampoo are worst for colour-treated hair?
Sodium lauryl sulphate (SLS) and sodium laureth sulphate (SLES) are the biggest culprits — these aggressive surfactants strip dye molecules from the hair shaft with each wash, accelerating colour fade significantly. High concentrations of alcohol, strong fragrance compounds, and harsh clarifying agents can also degrade colour and dry out the cuticle, making colour loss worse over time. The Rehues Colour Lock Shampoo is free of SLS, SLES, and parabens, using Cocamidopropyl Betaine as its gentle cleansing agent instead.
How often should I wash my coloured hair if I live in Singapore?
Singapore's heat and humidity mean most people need to wash daily or every other day — significantly more frequently than recommended for colour longevity. When washing this often, switching to a sulphate-free, colour-protective shampoo is essential, as the cumulative effect of frequent washing with a harsh formula will strip colour rapidly. Using a colour-depositing shampoo like the Rehues Colour Lock Shampoo matched to your shade helps replenish tonal pigment lost with each necessary wash.
Does Singapore's hard water make hair colour fade faster?
Singapore's tap water contains minerals, and while it is classified as soft to moderately hard compared to some other cities, mineral deposits can still accumulate on the hair shaft over time, dulling colour and contributing to a brassy or chalky appearance. Hard water minerals create a film on the hair that interferes with how light reflects off the cuticle, making colour appear less vibrant even when it hasn't technically faded. A chelating or colour-protective shampoo that addresses mineral build-up is particularly useful if you notice your colour looking flat between salon visits.
Is sulphate-free shampoo really necessary for coloured hair, or is it just marketing?
The evidence is clear: sulphates — specifically SLS and SLES — are ionic surfactants that interact directly with the dye molecules in colour-treated hair, causing them to detach and wash away with each use. Switching to a sulphate-free formula is one of the most consistently recommended steps by colourists for extending colour longevity, and it is not simply a marketing claim. The difference in colour lifespan between a standard sulphate-heavy shampoo and a gentle sulphate-free alternative is measurable and significant over multiple wash cycles.
Can I use the Rehues Colour Lock Shampoo on all types of colour-treated hair?
Yes — the Rehues Colour Lock Shampoo range covers four colour families: the Blue shade for bleached, blonde, highlighted, and ash-toned hair; the Brown shade for brunette, auburn, and warm-toned hair; the Pink shade for pink-toned colour; and the Grey shade for silver and natural grey hair. Each is formulated with specific pigments matched to its colour family, meaning the shampoo actively maintains your tone while the Colour Lock Blend™ and Bond Repair Complex protect the structure of colour-treated hair.
