For decades, hair washing has followed one unspoken rule: shampoo first, conditioner second. The order is so ingrained in the family line that most people rarely question if this is the only way to wash hair.
Now, a growing number of beauty enthusiasts are doing the opposite.
The latest haircare trend, known as the "shampoo sandwich", flips the traditional routine on its head by asking people to condition their hair before reaching for the shampoo.
Popularised by Ella Gross of K-pop girl group Meovv as she revealed this routine as one of her beauty secrets through Sungchan's E-terview YouTube show.
Following the viral shares of Gross' statement, the method has sparked numerous conversations online.
Unlike many viral beauty trends that encourage consumers to buy the latest product, this one simply requires using products already sitting on the bathroom shelf.
The trend also comes at a time when many people are struggling with seasonal hair concerns.
During summer, increased humidity, UV exposure, sweat and more frequent washing can leave hair feeling rough, tangled -- leaving the locks more susceptible to breakage.
While the scalp naturally sheds hair throughout the year, environmental stress can make strands appear thinner simply because damaged hair breaks more easily.
Washing without stripping
The routine follows three simple steps: conditioner, shampoo, conditioner -- you can remember it as the CSC method.
1. Condition: Applying conditioner first creates a light coating over the hair shaft before shampoo comes into contact with it.
2. Shampoo: The shampoo then cleanses the scalp and removes excess oil, sweat and product build-up
3. Condition: A final round of conditioner replenishes, moisturises and smooths the hair cuticle.
You may also replace the first conditioner with a hair mask for a more intensive treatment (Note: Hair experts generally recommend using masks as weekly treatments rather than substitutes for everyday conditioners).
As for the application of the conditioner, spread the product on the strands of your hair -- not the scalp itself -- to avoid weighing down the roots and causing buildup.
Interestingly, the concept is not entirely new. Many professional salons have long incorporated pre-conditioning treatments before shampooing, particularly for clients with heavily processed or damaged hair.
This growth of the shampoo sandwich on social media has just simply repackaged the practice into an easy-to-remember name.
What does this routine help?
The shampoo sandwich is often marketed alongside claims of reducing hair fall, but the science is more nuanced.
The routine does not prevent hair from shedding at the root -- that is influenced by genetics, hormones, nutrition and overall health. However, what it may reduce is breakage.
Hair is at its most vulnerable when wet. If strands are dry or dehydrated, friction during washing can create knots, making hair more likely to snap during brushing.
Hydrating the hair before cleansing helps reduce that friction, allowing strands to glide past one another more easily.
Rather than encouraging new hair growth, the shampoo sandwich focuses on preserving the health of the hair you already have.
Should you try this?
The method is particularly appealing for people whose hair has been through repeated colouring, bleaching, straightening or perming, all of which weaken the protective cuticle.
Those with fine hair that tangles easily may also notice softer, smoother strands after washing.
On the other hand, people with oily scalps may not enjoy the extra layer of conditioning.
Applying rich conditioners or masks too close to the roots can weigh hair down, leaving it looking greasy sooner than usual.
As with many beauty trends, results depend on hair type rather than internet popularity.
The shampoo sandwich reflects a broader shift in beauty, where consumers are becoming less interested in buying more products and more curious about using existing ones differently.
Whether it becomes a permanent part of people's routines remains to be seen. But its popularity suggests that sometimes, the biggest beauty trends are not about changing what we use, but how we use it.
