I Tried the Olaplex No.9 Serum—These Are My Honest Thoughts

I’m a huge fan of Olaplex and what the brand has done for people who chemically treat their hair. The in-salon system essentially strengthens strands against the damage that bleaching or chemical straightening can do to your hair’s health. And the at-home products are just as good for keeping hair healthy and making styling smoother, so I’m always excited when the brand adds to its range.

For me, there are some products in the range that stand out more than others. No.3 is an incredible pre-wash treatment. It strengthens and hydrates the hair without adding extra weight thanks to the key ingredient, bis-aminopropyl diglycol dimaleate, which builds bonds within the hair structure. You can leave it in for as little as 10 minutes, but I like to pop it on before a workout or overnight and then rinse it out when shampooing. However, the shampoo and conditioner were slightly underwhelming for me. They’re nice but not revolutionary.

Before using Olaplex No.9

The Olaplex product that I tend to use the most is No.6, the Bond Smoother. I use it as a heat-styling primer, applying a small amount to the lengths of my hair, and always see a dramatic improvement in smoothness and frizz control. So when I saw that the brand was launching a serum, I was a little confused. What was the product that I had been using for years, then?

I decided to try the new serum, No.9, in a silo without any other Olaplex products so I could see how it performs and if it can compete with the other styling products in the range. It’s described as a lightweight serum that not only strengthens hair but also protects it from free radicals, pollution and heat damage too. The first thing to note is the texture. It’s a clear lightweight gel that sinks into the hair quickly. Unlike No.6, you can layer it on, and you aren’t at risk of overloading your strands. I have short but thick, textured hair and used two full pumps.

I applied from root to tip on my towel-dried hair before detangling and then sectioning off for drying. This serum would layer really well under curl gel or cream if you are air-drying coils, curls or waves. I let my hair dry to about 70% and then blow-dried it without adding any further styling products. I was so beyond impressed with the way it made my hair feel. My strands were easy to detangle and post-blow-dry felt smooth, soft and hydrated even better than when I use No.6 post-wash. When I flipped around the bottle and checked out the ingredients, I wasn’t surprised to see the brand’s star ingredient, bis-aminopropyl diglycol dimaleate, really high up on the list. When comparing this with No.6, it makes sense that I preferred the way No.9 made my hair feel, as No.6 has far less of the brand’s trademark ingredient. Not only that but also No.6 has a lot of silicone in it, whereas No.9 is completely silicone-free.

After using Olaplex No.9

I happily use silicones in my hairstyling routine because as long as you wash your hair with shampoo to avoid too much buildup, silicones can help to keep out humidity and create a superficial shine on the hair. However, I prefer to stick to minimal silicone-based products throughout my routine to lessen the chance of build-up and spread out my washdays. This means that No.9 slots perfectly into any styling routine, whereas with No.6, I have to be more aware of the other products in my routine.

If I had to pick just one Olaplex product to use forever, it would be a tough choice between this new serum and my beloved pre-wash treatment, No.3. They both make washing and styling my heat- and bleach-damaged hair less of an arduous task. But I would say if you have been hooked on No.6, it’s time to clear room on your shelf for this new launch. You’re going to love it way more.

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