Do You Need Olaplex, K18 or a Hair Mask? Curly Hair Products by Hair Type
Few products cause as much confusion in curly hair care as Olaplex and K18. I regularly meet people with healthy, never-coloured curls who are spending a small fortune on bond repair, and people with bleached hair who've never heard of it. Neither brand is the problem. The problem is that nobody explains what these products are designed to do, or who they're for.
This is Part 2 of my curl aisle guide. In Part 1, I decoded the 11 curly hair product types and the four most people actually need. Here, I'll look at the extras that depend on the state of your hair: bond repair, hair masks, and how your routine changes if your hair is low porosity, chemically treated or belongs to a child. There's a quick self-check halfway down.
Quick answer: do you need Olaplex or K18 for curly hair?
Probably not, unless your hair has been bleached, coloured, chemically straightened or permed, or is damaged by regular high heat. Olaplex and K18 are bond-repair treatments designed to rebuild damage inside the hair from those processes. Untreated curls usually get more from a simple moisture routine. Take the 5-question self-check below to find out.
What Do Olaplex and K18 Actually Do?
Olaplex and K18 are both bond-repair brands. Their treatments are designed to repair damage inside the hair caused by bleach, colour, chemical services and heat. They're excellent tools for the right hair. They are not a substitute for moisture, and if your curls have never been chemically treated, there's much less for them to repair.
Olaplex
Olaplex is built around a patented bond-building ingredient designed to relink the broken disulfide bonds that chemical services, heat and styling damage. Its numbered range breaks down like this:
- No.1 and No.2: salon-only. Your colourist adds them during bleach and colour services to protect the hair while it's being processed.
- No.3 Hair Perfector and No.3PLUS Complete Repair Treatment: the at-home repair treatments, applied before shampooing. No.3PLUS is left on for 3 minutes and used 1 to 3 times a week, depending on damage. No.0 is a booster used before it.
- No.4C Clarifying Shampoo: a weekly clarifying shampoo that removes build-up, minerals and chlorine.
- No.4 to No.8: bond-maintenance versions of everyday products: shampoo, conditioner, leave-in styling cream, oil and mask.
To be fair to Olaplex, the brand says its treatments suit every hair type, including untreated hair, because heat, brushing and everyday wear also break bonds. My view is simpler. If you don't colour, bleach, relax or straighten, and you rarely use heat, you're unlikely to see a difference that justifies the price.
K18
K18 is built around its K18PEPTIDE, which the brand says repairs hair at a molecular level to reverse damage from bleach, colour, chemical services and heat. Its hero product is the Leave-In Molecular Repair Hair Mask, and the method matters:
- Shampoo, but skip conditioner.
- Towel-dry thoroughly.
- Apply 1 to 3 pumps, starting at the ends and working up.
- Leave it for 4 minutes, don't rinse, then style as usual.
K18 recommends using it for 4 to 6 washes, then as needed. Salons offer a professional K18 service, and the range also includes a Molecular Repair Hair Oil, a PEPTIDE PREP detox shampoo and DAMAGE SHIELD shampoo and conditioner.
Both brands work on the hair's internal structure. Curls still need moisture from a conditioner and a leave-in on top.
Do You Need Olaplex or K18? Take the Self-Check
Answer yes or no for the past 12 months, and your result will appear below.
- Have you bleached or lightened your hair, or had highlights or balayage?
- Have you used permanent hair colour?
- Have you had a keratin smoothing treatment, Brazilian blow-dry, relaxer or perm?
- Do you use a flat iron, curling wand or high-heat blow-dry more than once a week?
- Does your hair snap when you gently stretch a wet strand, feel gummy or mushy when wet, or have split ends that conditioner doesn't help?
Answer all 5 questions to see your result.
All no? You very likely don't need either brand. Put that money into the core four. Your clarifying shampoo already does the job of Olaplex No.4C or K18 PEPTIDE PREP.
Yes to 1, 2 or 3? Bond repair is designed for you. In the salon, ask your colourist about Olaplex No.1 and No.2, or a K18 service, during the treatment itself. At home, pick one: Olaplex No.3PLUS before shampooing 1 to 3 times a week, or the K18 Leave-In Mask for 4 to 6 washes and then as needed. You don't need the whole shampoo-to-oil range.
Yes to 4, but not 1 to 3? Start with less heat. The biggest fix is using heat tools less often and at lower settings. If your ends are already breaking, a short course of the K18 Leave-In Mask or Olaplex No.3PLUS can help.
Yes to 5 only? Check your balance first. With no chemical treatments or regular heat, breakage is more often a protein and moisture balance issue. Sort that out, and see a curl specialist before buying a bond-repair treatment.
Wuli isn't affiliated with Olaplex or K18, and this isn't sponsored. Product details are taken from each brand's own website as at October 2026.
Are Hair Masks Worth It for Curly Hair?
For untreated curls, usually not. Most hair masks are fortified conditioners, so if you condition every wash, you rarely need both. Masks really come into their own on chemically damaged hair, which needs the extra help. If that's you, one weekly mask or one bond-repair treatment is plenty. Choose one, not both.
Which Products Does Your Hair Type Need?
The right routine depends on the state of your hair. Here's how the core four change for low-porosity curls, chemically treated hair and curly kids.
Low-porosity curly hair
Low-porosity hair has tightly closed cuticles, so moisture struggles to get in and products tend to sit on top and build up. A quick test: drop a clean strand into a glass of water. If it floats, your hair is probably low porosity (more in our porosity guide).
- Clarify weekly, because build-up is your biggest enemy.
- Don't rely on co-washing alone. It can leave low-porosity and fine hair limp. Alternate it with a gentle sulphate-free shampoo.
- Choose a lightweight conditioner, and let it sit under a warm towel for a few minutes. Gentle warmth helps the cuticle open up.
- Use a light leave-in, and less of it, on soaking-wet hair. Skip heavy butters, oils and masks.
- Refresh with a light, water-based spray, not more cream.
Chemically treated hair (bleach, colour, keratin smoothing)
This is where the extras genuinely earn their place, because chemical services change the hair's structure.
- Cleanse gently with a moisturising, colour-safe shampoo or a co-wash.
- Condition every single wash.
- Add one weekly treatment: a moisture mask, or bond repair if your hair has been bleached or lightened.
- Keep your leave-in for daily moisture.
- Clarify less often and gently. Avoid detox shampoos on freshly coloured or very dry hair, and ask your stylist how long to wait after colour or a keratin treatment.
- Refresh with plain water if your hair is very dry or damaged. Sea salt and texture sprays suit healthier hair better.
Curly kids
Children's curls are usually in their healthiest, most natural state, so the prescription is always the same: as few products as possible.
- Wash once or twice a week with a mild shampoo.
- Use a lightweight, detangling conditioner every wash, and detangle only while it's in, with a wide-tooth comb or brush.
- Use one gentle styler at most, such as a small amount of curl cream on damp hair.
- Refresh with water in a spray bottle, and use a satin pillowcase to reduce friction.
Kids don't need masks, oils, bond repair or daily gel.
Frequently Asked Questions
Do I need Olaplex or K18 if my hair isn't coloured?
Probably not. Both brands' treatments are designed to repair damage from bleach, colour, chemical services and heat. If you don't colour or chemically treat your hair and rarely use heat tools, a simple moisture-focused routine will do more for your curls.
What is the difference between Olaplex No.3 and the K18 mask?
Olaplex No.3 and No.3PLUS are applied before shampooing and rinsed out, used 1 to 3 times a week. The K18 Leave-In Molecular Repair Mask goes on after shampooing, on towel-dried hair, and is left in without rinsing. Both are designed for hair damaged by chemical services or heat.
Should I use Olaplex and K18 together?
Most people don't need to. If your hair has been bleached, coloured or chemically treated, choose one at-home bond-repair treatment and use it as directed. Stacking several treatments adds cost and product without a clear benefit.
Are hair masks worth it for curly hair?
For untreated hair, usually not, because most masks are fortified conditioners and a regular conditioner already does that job. Masks are worth it for bleached, coloured or chemically straightened hair, used weekly or fortnightly.
Is co-washing good for low-porosity curly hair?
Not on its own. Low-porosity hair builds up product easily, so co-washing alone can leave it limp. Alternate co-washing with a gentle sulphate-free shampoo and clarify weekly.
Can I use adult curl products on my child's hair?
Many gentle adult products are fine for kids, but keep it minimal: a mild shampoo once or twice a week, a lightweight conditioner, and at most one gentle styler like a curl cream. Children's curls rarely need masks, oils or bond-repair treatments.
The Bottom Line
Olaplex and K18 are brilliant bond-repair tools for hair that has been bleached, coloured, chemically treated or heat-damaged, and mostly unnecessary for everyone else. Hair masks follow the same rule. Low-porosity curls need lighter products and regular clarifying, chemically treated hair needs gentleness and one weekly treatment, and kids need as little as possible. Start with the core four, and add extras only when your hair gives you a reason.
For the full picture, download my free Lazy-Proof Curly Hair Guide. Our Moisturising Co-Wash and Curl Cream are a gentle starting point for most hair types.