Honestly, I Love It: The Bond-Protecting Serum That Transformed My Hair

Welcome to Deep Reviews—your one-stop destination to discover the absolute best products and brands the beauty industry has to offer. Every month, the Who What Wear staffers you already know and trust will research, test, and review the market's most sought-after and buzzed-about products to see which formulas (of the hundreds up for consideration) are truly worth your hard-earned money and attention. You can expect honest, completely uncensored feedback and no-BS recommendations our hard-to-please testers endorse without reservations. To put it simply, stick with us, and buyer's remorse will be a thing of the past.

The majority of our Deep Reviews will feature our editors' honest, ultra-hot takes on wider product categories or multiple products within a particular beauty brand, but every so often, we'll sprinkle in a special single-product format called Honestly, I Love It. As the name suggests, these reviews will hone in on one standout beauty formula our editors quite literally can't shut up about. This time around, I'm highlighting Olaplex's No. 9 Bond Protector Nourishing Hair Serum ($30), a first-of-its-kind leave-in styling serum that has been shown to protect hair from pollution for up to 48 hours. 

I'm going to be honest with you. I have never known what to do with my hair. I have fine individual hair strands (making my hair prone to flyaways) but a ton of it (making it take nearly an hour to blow-dry). Growing up, I dreaded getting my hair cut because I was accustomed to stylists grumbling about how long it takes to both cut and dry my strands. When I style it on my own, my hair has a mind of its own. There's too much volume and not enough shine, and it chooses what direction it wants to go in regardless of how much heat I apply to it or product I put in. 

I've tried many, many hair products. Most promise smooth strands, reflective shine, and heat protection, but in my personal experience, many of them come up short for my thick hair. But that was until I got my hands on the Olaplex No. 9 Bond Protector Nourishing Hair Serum. 

Not to be dramatic, but when I first tried this serum, my hair was in need of mouth-to-mouth resuscitation. The ends were frayed, it was drying in very strange angles, and I just couldn't achieve any sort of shine when I was styling it myself. Unfortunately, the best adjective to describe my hair at the time was "dull." I picked up Olaplex No. 9 with a healthy dose of skepticism, but it quickly won me over. I'm now on my second bottle. As a beauty editor, I rarely buy products, but I'll do whatever it takes to keep replenishing this serum. I'm here to give you the full 411 on this rock-star haircare product—keep reading for all the details. 

I don't know about you, but I have a hard time trusting a hair product without hearing from an expert. The hair-product space is exploding, and like most spaces in the beauty industry, it's extremely oversaturated. So I tapped Christin Brown—a curl specialist, salon owner, and Olaplex ambassador—for her thoughts on the serum. 

Brown explains that Olaplex No. 9, when used on wet hair, is able to deeply penetrate the cuticle and do two major things: help relink disulfide hair bonds and infuse the hair with nourishing ingredients that are typically only found in skincare. 

"One of the most powerful benefits of Olaplex No.9 Bond Protector Nourishing Hair Serum is the pollution protection, which is huge," says Brown. "We may not be aware of the environmental damage that takes place continuously on our skin and hair daily, [but it] can lead to weakened strands and ultimately breakage or even hair loss."

One of the best things about this serum is that it can be used on all hair types and textures. But it's even better for curly hair since curly hair has more bonds, according to Brown. "The Bis-Amino technology that made Olaplex famous and created the bond-building category is included in the hair serum, so we're getting an efficacious amount of damage repair and strength as well for healthier strands," she says. 

When it comes to a product like this, it's all about the ingredients. Red algae from the South of France is a powerful antioxidant that works in tandem with a polymer to neutralize free radicals and defend hair from pollution, heat (up to 450°), UVA and UVB rays, and breakage. 

"I put this on the hair when it's wet to give the hair those antioxidant-rich benefits from the red algae while also being extremely helpful with detangling and style memory," says Brown. 

As you might expect from an Olaplex product, the serum contains the brand's patented Bond-Building technology, which works to repair existing damage while preventing future damage. While many hair products live in a different universe from skincare, this one leans into proven skin-friendly ingredients like panthenol and sodium hyaluronate, which help hydrate and smooth the hair. 

All of these ingredients work in tandem with each other for an entirely unique haircare product that gives hair an immediate—and visible—boost. After using this serum, you can expect shinier, softer hair, minimal flyaways and frizz, instant detangling, a faster blow-dry time, and style memory.

Let's talk about my own experience using the product. First of all, a little goes a long way, so one bottle will last you upwards of six months. At least, that's how long my first bottle lasted me. This product is best used on wet hair, so I apply one pump first thing after I get out of the shower. It has the kind of consistency you might expect from a hyaluronic acid skincare serum—gel-like, bouncy, and lightweight. 

When I typically blow-dry my hair, I'm used to following with a hot tool if I want to do damage control on flyaways and frizz. It's a vicious cycle since more heat ultimately leads to more damage, which leads to even worse-behaving hair. After applying Olaplex No. 9, however, I see a noticeable difference in the way my hair dries and how it looks.

From a styling perspective, Olaplex No. 9 helps cut down on my blow-dry time like no other product I've ever used. Remember how I said it can take me nearly an hour to dry my hair? When I use this serum, that hour turns into about 20 minutes. You can also see an immediate difference between my hair sans serum versus with it.

I mean, just look at my before-and-after pictures. On its own, my hair looks duller and damaged and has tons of flyaways. When I use the exact same setting on my blow-dryer along with a pump of Olaplex No. 9, my hair is smoother, shinier, and easier to brush through, and it even looks healthier. After adding in curls, I might as well have gotten a professional blowout, and I can promise you that my hair never—and I mean never—looks like this when I style it on my own. Honestly, I love it, and ever since trying it, I have rarely skipped it after washing my hair. 

Discover Other Products in the Olaplex Portfolio

Unlike most hair oils (which have a tendency to weigh down hair and make it feel greasy), Olaplex's sinks into hair instantly without giving it an oily feel. It's formulated to boost shine, protect against heat, and lock out frizz. It's also incredibly lightweight, so it's an easy addition to any haircare routine. 

How to use: Apply a few drops of this oil from the mid-shaft of the hair to the tips before styling. You can use it on wet or dry hair.

This hair treatment is essentially the first step for rebuilding bonds and strengthening hair. It can be used on its own, but it works best when used in tandem with the Olaplex No. 3 Hair Perfector.

How to use: Apply to dry hair by fully saturating strands from root to tip. Let it sit for 10 minutes and then apply the No. 3 Hair Perfector and let it sit for an additional 10 minutes before washing hair. Use one to three times per week.

Olaplex's Hair Perfector works best when it's used with the No. 0 Intensive Bond Building Hair Treatment. This innovative treatment strengthens and repairs damaged hair by penetrating the hair shaft.

How to use: Layer on top of the No. 0 Intensive Bond Building Hair Treatment and let sit for 10 minutes before washing out, or apply directly to towel-dried hair and leave on for at least 10 minutes. Use one to three times per week.

Next, Honestly, I Love It: The New Face Mist That Banished My Redness—Instantly