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I always loved chemistry class in high school, so much so that I’m pretty sure my teacher was sad to learn I didn’t become a scientist in real life (RIP to that dream). However, beauty and chemistry are pretty intertwined—take, for example, the the buzzy, best hair-bonding treatments like Olaplex and K18. They're kinda like protein treatments and deep conditioners, but so much better. But do you know what they do, how they work, and why you absolutely need one in your routine, stat?
A little background: Bonds are the formation of your overall hair structure, says hairstylist Cynthia Alvarez. "There are three bonds that make up the hair structure—hydrogen, ionic, and covalent,” she says. “While they help give hair its strength, bonds can be weakened and ultimately broken by damage, like bleaching and chemical treatments." And when these bonds break, that weakens the structure of your entire hair strand, causing a slew of issues, says hairstylist Rogerio Cavalcante. “Your hair loses strength, becoming more prone to breakage and split ends, can even make your hair appear frizzy and less smooth, losing its shine and healthy look," he says.
But with the help of ~science,~ the best hair-bonding treatments use high-tech strengtheners to actually repair those broken bonds to seal split ends, revive chemically-processed hair, and give you the shiniest, healthiest hair ever. Hard to believe, right? Well, over the past few weeks, I put dozens of hair-bonding treatments to the test to see how well they could mend my damaged hair. Just feast your eyes on some of the top formulations:
Our top picks for hair-bonding treatments in 2024:
Best Hair Bonding Treatment Overall
K18 Leave-In Molecular Hair MaskRead more
Best Hair Bonding Treatment Oil
Olaplex No. 7 Bonding Hair OilRead more
Best Leave-In Hair-Bonding Treatment
Living Proof Triple Bond ComplexRead more
Any of the following bonding treatments will give you the best hair of your life (promise!). See, what’d I tell ya, science can be fun!
1
Best Hair Bonding Treatment Overall
K18 Leave-In Molecular Hair Mask
Pros
- Only requires four minutes of your time to use
- Hairstylists and derms constantly recommend it
- Works on legit all hair types, from ultra-fine to coarse and curly
Cons
- Most expensive formula on this list (but comes in a mini size!)
I owe my long, strong hair to K18. I regularly dye my hair and use hot tools, resulting in quite a bit of damage. But this fast-acting mask basically repairs my hair in four minutes flat—yes, really! Developed with the brand’s patented K18 peptide (which is filled with whopping 123 strengthening amino acids), the now cult-favorite mask restores hair from the inside out by reconnecting the bonds, making each strand healthier. The results get even better with continued use, so I make sure to smooth a dime-sized amount from roots to ends once a week.
- Key Ingredients: K18's patented peptide formula, citric acid, wheat protein
- Hair Type: All
- How to Use: Apply to damp hair after shampooing (don't condition), then leave on for four minutes before styling
- Size: 1.7 oz
Glowing customer review: “I’ve been using the K18 for several weeks and I’m totally amazed how much this product has helped my damaged bleached curls. If your hair is toast, try it! Worth the $$."
2
Best Hair Bonding Treatment Oil
Olaplex No. 7 Bonding Hair Oil
Pros
- Uses the O.G. Olaplex bonding ingredient
- Only need to use a few drops for my long, thick hair
- Adds major shine and smoothness
Cons
- I wish the bottle were bigger
We couldn’t have a list of bonding treatments without calling out Olaplex, the brand that pretty much took the term "bonding" mainstream. While all of their products can help revitalize and strengthen your hair, this oil is the most versatile I've tested. Sure, it can restore my damaged hair in the long run, but I especially love that it can immediately refresh day-old hair by smoothing flyaways, enhancing shine, and intensifying my color. Best of all, I only need three drops max to make a difference, so though the bottle is small, it will last me a v-long time.
- Key ingredients: Bis-aminopropyl Diglycol Dimaleate (Olaplex's patented bond-building ingredient), grapeseed oil, green tea oil
- Hair type: All
- How to use: Smooth two to three drops all over damp or dry hair
- Size: 1 oz
Glowing customer review: “Great hair oil. You only need a little bit and it makes my hair really nice and shiny. Olaplex products are great in general. Definitely recommend for frizzy and damaged hair.”
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3
Best Leave-In Hair-Bonding Treatment
Living Proof Triple Bond Complex
Pros
- I can see (and feel!) and immediate difference
- Acts as a heat protectant too
- Silicone free, which is great for fine hair types
Cons
- Bottle is small, which some testers didn't love for the price
The one thing that annoys me the most about my hair are my scraggly ends (why, WHY are they so hard to fix?). It’s unrealistic for me to get a trim every six weeks, so this leave-in has become my secret weapon for keeping my ends fresh. The deeply nourishing formula zips up split ends almost like magic and smooths out the rest of the hair cuticle so frizz and tangles become a thing of the past. As a bonus, this serve as a heat protectant to prevent future damage, too.
- Key ingredients: Jojoba oil, citric acid, castor oil
- Hair type: All
- How to use: Comb one to two pumps through lengths of damp hair once a week, and don't rinse
- Size: 1.5 oz
Glowing customer review: “This hair treatment made my hair so much healthier! I was struggling from bleach damage and overall heat damage and this LEAVE IN IS AMAZINGGGG!! My hair is healthy, shiny, and grew back quickly! I highly recommend 10/10”
Pros
- Only have to use a lil bit
Cons
- Have to apply before shampooing, which adds an extra step
Many bonding treatments will cost you a pretty penny, but this drugstore pick is less than $15 and does the same thing. Not only will you start to see results after first use, but it’s super easy to use, too. Smooth a dollop on your hair before shampooing, and then rinse it out before continuing on with your wash day. Its main hydrator is glycerin, which absorbs into your hair quickly without leaving it greasy.
- Key ingredients: Lactic acid, glycerin
- Hair type: All, but might not be hydrating enough for very dry hair without other moisturizing products
- How to use: Apply on dry hair before shampooing, let sit for 10 minutes, then rinse
- Size: 4.5 oz
Glowing customer review: “I can not believe how fantastic this product is. My hair feels so soft and feels healthier everybody needs to try it.”
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Pros
- Fastest treatment EVER (you only need 10 seconds)
- Liquid formula with nozzle applicator is easy to disperses through hair
Cons
- If you don’t fully rinse, it can make hair greasy (according to reviews)
If I’m being honest, I barely have time to wash my hair, let alone sit around for 20 minutes with a mask—which is why I’m convinced Aveda created this treatment for those of us short on time. After dousing your strands with the liquid formula, you only need to give it 10 seconds to help repair, soften, smooth, and enhance shine. It uses two acids (lactic and tartaric) to help smooth your cuticles, then moisturizes and seals with a slew of oils.
- Key ingredients: Avocado oil, lactic acid, tartaric acid, coconut oil
- Hair type: All
- How to use: Apply a generous amount on the lengths of your wet hair while showering, let sit for 10 seconds, then rinse
- Size: 5 oz
Glowing customer review: “I had a bad bleach job and this is literally saving my hair! It went from feeling dry and straw like to hydrated and bouncy! It also brought back my curl definition, which makes me so happy! It's so easy to use and incorporate into my hair care routine, I feel like my hair gets stronger every time I use it. Highly recommend!”
6
Best Hair-Bonding Treatment Leave-In
Redken Acidic Bonding Concentrate Leave In Conditioner
Now 17% Off
Pros
- Uses citric acid to help rebuild bonds and smooth hair
Cons
- Might be a tad too rich for those with super-fine hair
Redken super-charged this bonding formula with citric acid to really restore the most damaged, color-processed hair. Quick science lesson: Acid—specifically citric acid—works as a bond builder to boost strength and smooth out the hair cuticle. Beyond what it can do for your hair, it also balances out the pH of your scalp to prevent dryness and dandruff (the more you know!). When you run this lightweight leave-in through your hair before blow-drying, it'll help repair damage over time, as well as smooth with silicones and hydrate with glycerin.
- Key ingredients: Citric acid, glycerin, silicones
- Hair type: All, but contains silicones, so keep in mind if you follow Curly Girl Method
- How to use: Smooth through clean, damp hair from root to end, then style as normal
- Size: 5.1 oz
Glowing customer review: “This is the best leave in that I ever bought! My hair is extremely dry after two rounds of bleach. This Leave In Conditioner left my hair feeling like I just left the Salon! It feels and looks 100 X’s healthier! It absorbs into my hair nice and leaves no greasy feel. And it smells soooo good! I recommend it to everyone!”
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Pros
- Beyond repairing hair, it also helps define curls
Cons
- Some reviewers say the scent is a little unpleasant
You already know your curls are v fragile. This rich mask—which was specially formulated for curls—goes above and beyond simply strengthening and restoring hair. Along with repairing broken hair bonds, it seals split ends, prevents new ones from forming, deeply conditions, and helps define curls and coils.
- Key ingredients: Succinic acid, arginine
- Hair type: All curls and coils, but might be a bit too heavy for fine curls
- How to use: Apply to clean, wet hair and let sit for 15-20 minutes before thoroughly rinsing
- Size: 8 oz
Glowing customer review: “So I have been straightening my hair for YEARS and randomly decided I wanted to embrace my natural hair. After trying many different products and methods of styling I looked on Amazon and found this product. I used it once, and didn’t put much effort into styling after it, still I saw a huge improvement in the hydration and curls. Although it still has a lot of frizz due to humid conditions I am so happy with the results!!”
8
Best Shampoo and Conditioner Hair-Bonding Treatment
L’Oréal Paris Bond Repair Shampoo and Conditioner
Now 15% Off
Pros
- Can be used daily
- Shampoo is sulfate-free
- Conditioner smoothes with silicones
Cons
- Scent could be better, per testers
Sometimes all I want to do is shampoo and condition my hair without adding any other steps to my routine— is that too much to ask for?! L'Oreal gets it with this affordable duo that's spiked with bond-building citric acid. When used together, the formulas repair and rebuild hair bonds from the inside out. You can use it every day (which can’t be said for other bond-building treatments) and hair begins to look smoother and shinier with each wash.
- Key ingredients: Citric acid, sunflower seed oil
- Hair type: All, but doesn't comply with CGM, FYI
- How to use: Shampoo and condition hair
- Size: 6.8 oz
Glowing customer review: “I have very fine, dry, frizzy 2C/3A hair. My hair cannot hold moisture to save its life. I’ve tried a bunch of options and finally heard about this set. I’m a believer that most shampoo and conditioners are basically the same when it comes to my hair. They make literally no difference. But finally I tried this one. It actually does make a difference in my hair. My hair stays wet longer and feels better.”
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9
Best Affordable Hair-Bonding Treatment
Garnier Fructis Hair Filler Bonding Inner Fiber Repair Pre-Shampoo Treatment
Now 30% Off
Pros
- Least expensive hair-bonding treatment on this list
- Easy to find at most drugstores
Cons
- Some reviewers say the results aren’t as noticeable as other treatments
You know how vitamins heal your body from the inside out? This inexpensive pre-shampoo treatment works similarly for your hair. Just a tiny bit of the serum-like pre-wash penetrates your hair strands, rebuilding broken bonds from within. Using a blend of citric acid and strengthening peptides, it smooths your hair's cuticle, creating a soft, smooth, and shiny finish. And it does it all for less than $10 (!!).
- Key ingredients: Peptides, citric acid
- Hair type: All
- How to use: Apply to dry hair three to five minutes before shampooing
- Size: 10.1 oz
Glowing customer review: “The best hair repair ever. It only takes 5 min. Leaves the hair shiny, smooth, and repairs any hair damaged at any level. My savior. Try it, you will never regret it.”
Pros
- So easy to spritz onto your hair
- Only needs to be used once or twice a week
Cons
- Have to mix the formula in the bottle yourself
You may not have heard of Epres, but you definitely know another haircare brand that founder Eric Pressly helped develop (Hint: It rhymes with Smolaplex). With over 100 bond-building patents under his belt, Pressly’s latest venture takes bond-building to the next level thanks to its user-friendly format. Rather than having to massage a mask or serum into your hair, all you have to do is spritz this throughout your strands one to two times a week. Within 10 minutes, the powerful formula begins working to repair hair structure, reviving strands and giving you the best head of hair… maybe ever.
- Key ingredients: Biodiffusion bond repair technology
- Hair type: All
- How to use: Generously spritz dry or wet hair, then shampoo and condition
- Size: 10.41 oz
Glowing customer review: “I don’t really have damaged hair but I have dry brittle hair so I tried this for softness and strengthening. WOW, my hair is silky, silky soft. I use it a few times a week at night and leave it under a silk bonnet, and wash the morning after. Probably the best product I’ve tried in years! And there’s really no fragrance which I love. I seriously recommend this. You’re going to see the difference in shine and softness.”
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11
Best Dry Hair-Bonding Treatment Mask
IGK Antisocial Overnight Bond-Building Dry Hair Mask
Pros
- Can be used on dry hair
- Gives my hair a tousled, textured look while strengthening hair
Cons
- Doesn’t immediately enhance shine
I’ll admit I can be reaaaalllly lazy with my hair. Styling takes so much effort some days, and most of the time I can’t even be bothered to sit with a hair treatment in. When I want a good hair day without trying, this innovative mask comes to the rescue. It essentially works like a dry shampo, but does some heavy-duty repairing and softening rather than simply refreshing my hair. It’s literally one of the easiest hair products I’ve ever used because I can just spray and relax—and it actually enhances my style too! While effort is at a 0, results exceed 100.
- Key ingredients: Vegan silk proteins, pea protein, peptides
- Hair type: All
- How to use: Spray on dry hair in sections, then comb through
- Size: 5 oz
Glowing customer review: “LOVE THIS FOR SOOO MANY REASONS! it hydrates my hair, will control the thick, frizzy mess that is my hair after sleeping in wet hair. its like the best perfume for my hair! its great for was days, or even day 7 hair!!! 1000/10 RECOMMEND!!”
Pros
- Helps keep my hair color vibrant
Cons
- Can make hair flat if you use too much
Listen, I know that coloring my hair is damaging it more than anything else, but I can’t (and won’t) stop. Thankfully, Madison Reed gets it, and on top of creating ammonia-free natural hair dyes to minimize harm, they also have this bond-building treatment. The all-in-one formula strengthens, repairs, reduces breakage, and protects color from fading. That last feature is so crucial for those who regularly dye their hair—like moi—so you can go longer in between salon services.
- Key ingredients: Glycerin, panthenol, black spruce extract
- Hair type: All, but especially color-treated hair
- How to use: Apply 2-4 pumps to clean, towel-dried hair
- Size: 4 oz
Glowing customer review: “Love, love, love! I have fine hair. Most products leave it limp. This product gave immediate volume, as well as silky, smooth, and full body from the very start. I simply love running my fingers through my hair! And it looks absolutely beautiful the following day. Can't wait to see the effects over time.”
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Pros
- Prevents knots and tangles
- Leaves hair soft and shiny
Cons
- The bottle is kinda small for how much you need to use
If you struggle with tangled hair—which, btw, is a telltale sign of damage—this handy little spray will act as a detangling bond-builder to mend strands and diminish those knots once and for all. Spritz the nourishing formula through towel-dried hair (and don’t be afraid to use a lot; I recommend 10-20 sprays!) and watch as your brush glides through without catching or snagging.
- Key ingredients: Malic acid, panthenol, squalane
- Hair type: All
- How to use: Apply to towel-dried hair and comb through
- Size: 1 oz
Glowing customer review: “I have long hair but they are a bit damaged. I used about 10-15 sprays of Wella Professional repair and I could comb my hair very easily without breaking many hair. It left my hair so soft and smooth and smells great too. I have used it only twice but can see a lot difference already.”
14
Best Hair-Bonding Treatment for Shine
Bumble and Bumble Bond-Building Repair Treatment
Pros
- Uses hella oils to add major shine
Cons
- Might be too heavy for fine hair types
Few hair treatments are sweeter than this pick from Bumble and bumble, which calls upon three different types of honey to nurture and restore hair. The natural ingredient is able to sink deeply into the hair cuticle to repair from the inside out while also reinforcing the strands to prevent future breakage, leaving hair softer. Aside from how hair feels post-treatment, this also dramatically increases shine and rivals the look of a professional glossing treatment.
- Key ingredients: Avocado oil, meadowfoam seed oil, lactic acid, squalane
- Hair type: Dry, damaged, coarse
- How to use: Apply to damp hair, leave on for 5 minutes then rinse.
- Size: 4.2 oz
Glowing customer review: “Don’t walk, run!!! I received this product as a free sample and it was life changing. It may seem a little expensive but I am telling you, it is worth every penny. It’s like a perfect mix of all the best hair mask /conditioner I’ve ever tried!”
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15
Best Customizable Hair-Bonding Treatment
Function of Beauty Pro Bond Repair Custom Leave-In Treatment
Pros
- Customizable with nine potential concentrates
Cons
- Concentrates are sold separately (but are only $4 a piece)
Custom hair care for under $30? Sign me up, bb. At the core, this bond repair leave-in treatment reverses damage, but you can add special concentrates to tackle your hair concerns. Struggle with frizz? Pop in the frizz-control concentrate. Hair feeling extra dry? No worries, a little moisture boost can help. Choose between nine concentrates to create the perfect reparative potion catered just for you.
- Key ingredients: Babassu oil, amaranth extract,
- Hair type: Straight and wavy (but also available in a curly/coily option)
- How to use: Apply to clean, towel-dried hair and style as usual
- Size: 4.3 oz
Glowing customer review: “I’ve been using this product twice a week for 3 months. I have an oily scalp but dry ends. I added frizz and shine to the leave-in. My hair is softer and smoother and for some reason my scalp doesn’t get as oily as it used to be.”
Pros
- Foam texture feels lightweight on hair
- Replaces conditioner, so no extra step required
Cons
- Probably not nourishing enough for thick or dry hair
“Many bonding treatments are rich, thick conditioners and leave-ins that end up being too heavy for fine hair,” says Alvarez. That's why this lightweight option was especially made for fine hair types. "I personally have never seen anything like it, and love the slip it gives hair while leaving it hydrated and prepped for styling," she adds. The bouncy foam conditions hair without weighing it down (not to mention, it’s super fun to use!) all while repairing broken hair bonds in the process.
- Key ingredients: Glycerin, castor oil
- Hair type: Fine, damaged
- How to use: Apply to wet hair in place of conditioner
- Size: 8.4 oz
Cosmo review: “I am very particular with conditioning products, because although my hair is bleached and curled almost daily, it is so oily and prone to getting weighed down. But this proves my fine hair can have it all, baby! It helps smooth and hydrate my ends, but doesn't make them feel oily at all." — Beth Gillette, beauty editor
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Pros
- Rich mask makes my hair feel so soft and moisturized
- Available at drugstores (!)
Cons
- Too heavy for some fine hair types
It’s really difficult to restore straw-like hair (you’re almost always better off going in for a chop, babes), though Pantene is over here working near-miracles with its aptly named Miracle Rescue Mask. This mask majorly repairs my damaged hair with citric acid, but feels rich and nourishing on my hair, thanks to moisturizing melting pearls that envelope your hair in mega moisture and help rebuild broken bonds.
- Key ingredients: Histidine, panthenol, citric acid
- Hair type: Dry, coarse, thick, damaged
- How to use: Apply to clean hair, leave on for five to seven minutes, then rinse
- Size: 10.1 oz
Glowing customer review: “Smells amazing and works well. Has the same consistency as conditioner and makes your hair 10x as soft. Works as a moisturizer & detangler for your hair. Good price, too.”
What is a hair bonding treatment?
Generally speaking, “hair-bonding treatments are designed to repair and strengthen the bonds within the hair shaft,” explains Cavalcante. “They do so with ingredients that can penetrate the hair and relink broken bonds, thereby restoring the hairs’ strength, elasticity, and overall health.”
So, if you have damaged hair from color or chemical treatments, heat styling, or overall mechanical damage from just existing as a human with fragile af hair, then you can benefit from a hair-bonding treatment to help restore your hair, bringing us to...
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How do you know if your hair needs a bonding treatment?
Anyone can benefit from a hair-bonding treatment, tbh, but “if you regularly treat your hair with chemical services and heat styling, you should be using a bonding treatment,” says Alvarez. “Heat and chemical services can lead to breakage, split ends, and overall limp hair, and the bonding treatments can help combat this."
That said, even if you don’t color or heat-style your hair, it wouldn’t hurt to add a bonding treatment to your routine. In fact, hairstylist Miguel Luis says that if your ends are splitting, your hair doesn’t look as shiny as it used to be, or you have lots of shedding when brushing your hair, you might also benefit from a bonding treatment.
How to choose the best hair bonding treatment for you:
Consider your hair type
It’s true that most bonding treatments will work for all hair types, though it doesn’t hurt to factor in your hair type. For example, some formulas, like the DevaCurl CurlBond Re-Coiling Treatment Mask, are designed especially for curly hair, while others, including the Function of BeautyPRO Bond Repair Custom Leave-In Treatment for Damaged Straight and Wavy Hair, will work best for straight or wavy hair.
Beyond your hair type though, think about the level of damage you’re dealing with. If you regularly chemically process your hair (i.e. bleach the sh*t out of it), it may be better to opt for something that really caters to that damage. Experts swear by the K18 Leave-in Molecular Hair Repair Mask, though the Pantene Miracle Rescue Hair Mask also helps restore hair at a more budget-friendly price.
Think about your pre-existing routine
Incorporating a bonding treatment will obviously add another step to your routine, so if you like to keep things simple, you’re probably better off purchasing a product that doesn’t require a lot of time and energy to work. Some masks require 15 to 20 minutes to sit (Idk who has that kind of time, but not me). So, if you want a quick fix try the Aveda Botanical Repair Bond-Building Flash Treatment or IGK Antisocial Leave-In Dry Hair Mask. Both of these products only take seconds to start working.
Mary Honkus
Mary Honkus is a freelance writer who covers beauty, home, fashion, health, and wellness (just call her a jack of all trades!). She has held staff roles at Real Simple, People, and InStyle, and her bylines can be found in numerous other publications. When she's not testing the latest and greatest products, she can be found chilling on her Hell's Kitchen rooftop, checking out NYC's hottest new restaurants, or recording her podcast Good Trouble NYC. Follow her on Instagram.