An Honest Review of Olaplex No. 9 Serum Before You Buy | Well+Good (2024)

The shampoo, the myth, the legend: Olaplex. Known for its proprietary bond-building formula that strengthens and protects hair, Olaplex products are coveted by folks looking to repair color-treated and/or damaged strands, and beloved by stylists who want to give their clients a best-in-class blowout. Most recently, the brand launched Olaplex No. 9 Bond Protector Nourishing Hair Serum ($28), which uses bond-building tech along with red algae, an ingredient normally found in skin care (we'll get to that in a few seconds).

While it launched in late March, I wanted to test out the serum on my own hair for at least a month to see if could really help improve my hair health in the long run—not just after one or two uses. Spoiler alert: If you haven't, you can go ahead and add this bottle to cart, Olaplex makes good on its promises.

What makes the serum stand out is its unique triple-action formula that strengthens, protects, and smooths. Olaplex's bond-building tech repairs and nourishes dry, frail strands while the serum's infusion of red algae extract works overtime by bonding to hair and defending follicles against damage from hot tools, pollutants, and UVA and UVB rays. According to the brand, it keeps your hair protected for up to 48 hours.

Plus, the brand's entire line works with all hair types. "The reason why Olaplex is good for all hair types is because hair bonds are agnostic regardless of gender, age or ethnicity," says celebrity hair colorist and Olaplex ambassador, Bianca Hillier. "Curly and textured hair has more disulfide bonds, and is more susceptible to environmental, mechanical, and chemical damage." The multi-patented formula keeps follicles well-guarded from harsh elements and also reinvigorates strands from the inside out, which is why the end result is shiny, silky, smoother hair.

What my experience with Olaplex No. 9 has looked (and felt) like

I've been testing No. 9 for about a month (I've used it around four or five times in total), and, similarly to all Olaplex products, have noticed a difference right away. What made this experience different (and what made No. 9 "pass the test" for me) is that I just got extensive highlights, so large portions of my naturally dark brown hair have been bleached and toned. So, I was really hoping the serum would make my new hair—which I love, but feels dry and hay-like—healthier, softer, and less prone to breakage.

No. 9 understood the assignment, and we got off to a great start the first time I used it. After applying the serum to wet strands, I blow dried and styled my hair (which was easier to do than usual, since the serum helped unravel any tangles and made strands easy to comb through). I noticed less hair on my brush, and when I was done, my hair looked shinier and soft to the touch. And it stayed this way for three days until my next wash.

I use it after every wash at this point—and especially before an event when I want to give my hairstyle a bit more oomph. Here's me two weeks ago at a beauty launch:

On its own, my hair is naturally wavy and frizzy. It always has been, but the bleach and constant use of heating tools (blow dryer, straightener, and curling iron) has put it in a constant state of "Mia Thermopolis before her Princess transformation." With No. 9, I can achieve a smooth, bouncy, sleek 'do, and I can even brush my hair without messing with the finished product. And! On days when I choose not to do anything with my hair post-wash, I've noticed my strands still retain shine and some smoothness—and my blonde highlights are as vibrant as ever. So, this stuff really does work in the long run when you continue to use it.

The texture of the serum itself is lightweight, and a little bit goes a long, long way. I use about a quarter-sized dollop on my whole head of hair, which is near boob-length and is of average thickness. The serum is slick, not goopy or sticky, and it's easy to work through your strands to make sure every single one is evenly coated.

Before I had a chance to try No. 9, Hillier advised me, "Once you comb through damp hair you can gradually apply a small amount from the ends up to the mids, then the root. Apply more as needed for thick or long hair." She also added, "The serum works well with both thermal styling and air drying. You can use this product wet or damp but I prefer damp hair prior to heated styling tools. "

Conclusion?

It's hard to go wrong with any Olaplex product (the collective hype truly is well-deserved), and the No. 9 is no exception. I know I'll be using every last drop. Good thing auto-subscribe exists!

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