If you’re a haircare fanatic, you’ll know that Olaplex makes some of the best products on the market. Whether it’s the pre-shampoo No.3 treatment (£19.50, Amazon.co.uk) or the cult No.7 bonding oil (£22.40, Amazon.co.uk), everything I’ve tested from the brand has transformative results – it’s no surprise Kim Kardashian and Margot Robbie are fans.
Now, less than three months since the launch of Olaplex’s No.0.5 scalp longevity treatment (£41, Sephora.co.uk), the brand has treated us to two more 2025 releases designed for fine hair. The new drops are variations on the existing No. 4 and 5 shampoo and conditioner (£56 for both, Cultbeauty.co.uk), swapping heavier conditioning ingredients like amodimethicone (a type of silicone) for lighter alternatives such as behentrimonium chloride (derived from rapeseed).
I wanted to see how this change, alongside more than 50 other ingredient modifications, impacted the feel and appearance of fine hair. As one of the first people to get my hands on the new fine bond maintenance formulas (£30 each, Olaplex.com), I did just that. Scroll on for my first impressions after several weeks of hair washing.
How I tested
After receiving Olaplex’s new formulas, I immediately got to work using the fine hair-specific shampoo and conditioner. I solely used these products on wash days for several weeks and made sure to rinse and repeat at the shampoo stage. As I do in my usual conditioning routine, I then left the No. 5 fine bond maintenance conditioner on my hair for two to three minutes to do its thing while combing through any tangles in the shower. I then rinsed and blow-dried as normal.
Why you can trust IndyBest reviews
In addition to heading up The Independent’s guide to the very best shampoo and conditioners, I’ve reviewed dozens of hair wash formulas, including those by Monday and The Ordinary. I’ve also covered Olaplex’s blow-dry mist and the top deals on the brand’s bestselling No. 3 hair perfector. I have plenty of know-how when it comes to key ingredients and have interviewed a variety of trichologists and expert hair stylists in my years as a beauty journalist.
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Olaplex no.4 fine bond maintenance shampoo
Formula
Compared to its universal no.4 predecessor, Olaplex’s new no.4 shampoo for fine hair takes a gentler approach to cleansing. For instance, the new formula removes silicones to prevent weighing down strands and uses surfactants that are less likely to strip away natural moisture, like the sodium laurel sulphate used in the original product. The new iteration does away with the heaviness of avocado and grape seed oils, swapping these for more lightweight nourishment using apricot oil, which also works to strengthen. The formula is also designed to thicken your hair with a combination of agents that coat the hair shaft, including sclerotium gum, an addition to the formula, which acts as a body-building, flexible and volumising film. The no.4 fine iteration boasts the same candy-sweet scent as the original and appears identical.
Performance
I was pleased to report the same reliable lather I’ve grown used to with Olaplex and though it takes a little graft to rinse it out of the hair, it easily tackles oily roots and build-up. I’d argue that you can feel the formula working to thicken the hair as you massage it into the scalp, with the texture of the hair and bubbles at this stage akin to a chalky texturising spray.
After blow-drying, my hair felt fresh, soft and clean. I was also surprised at how well the thickening agent worked, as my roots appeared lifted and my entire head of hair noticeably fuller even after just one wash. After consistent use, these effects only amplified, and I found that the thickness of my hair pretty much doubled in a matter of weeks.
Buy now £29.99, Uk.olaplex.com
Olaplex no.5 fine bond maintenance conditioner
Formula
Much like the shampoo above, Olaplex’s new no.5 fine conditioner swaps silicones for lighter forms of hydration (e.g. behentrimonium chloride) and oils for ingredients like niacinamide. It also adds hydrolysed quinoa, which, being rich in peptides, smooths the hair cuticle and provides a protective, body-boosting film. Together with the shampoo’s sclerotium gum, these wash formulas set out to thicken the hair on a strand-by-strand basis.
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One of the key draws of Olaplex products is the brand’s patented bond-building ingredient (bis-aminopropyl diglycol dimaleate), which fans will be pleased to learn is still present in the new fine hair formula. However, there’s more of a focus on volumising than repair with this new iteration, so there’s less noticeable restoration.
Where the universal conditioner contains ingredients designed to reduce frizz and breakage, the fine hair formula focuses more on those that help build volume and minimise static. A few of the original repair elements have been sacrificed to keep the formula light and fine hair-friendly.
Performance
How do these changes translate to a real-world testing scenario? Overall, I found the new conditioner to be effective. It reduced breakage, detangling and softening my hair with ease. I loved the reformulation’s lightweight finish, and there was no static, even when using my boar bristle brush (a repeat static offender).
Admittedly, I did notice that my strands appeared less smooth when compared to using the original Olaplex conditioner. Where silicones can help to flatten split ends and mid-length breakage, the fine hair conditioner was lacking in this department.
Buy now £30.00, Uk.olaplex.com
The verdict: Olaplex fine bond maintenance shampoo (no. 4) and conditioner (no. 5)
On the whole, I was impressed with the lifting effects of the no. 4 and 5 fine hair formulas and saw a noticeable difference in the thickness of my hair after just one wash. My hair felt bouncy from the roots, and the individual strands were left light and fluffy. While I appreciate the need for compromise when making changes, these products did lose some anti-damage effectiveness in the process of tailoring them to fine hair. Though static stayed at a minimum, I was aware of mid-shaft splits and dry ends in a way that I hadn’t been when using the original, silicone-rich shampoo and conditioner. Would I buy it again over the old formulas? Definitely, but I suggest pairing it with the bond-building power of the No.3 pre-shampoo treatment for an extra boost.
