Biotin
Nail Strengthener
Concentrated strength for weak, bendy nails.
Strength, right where your nails need it. This concentrated serum sinks straight into thin, soft, bendy nails, reinforcing the keratin structure and sealing in moisture so they grow firmer, stronger and far less likely to bend or snap. Especially for nails left fragile by gel, acrylic or glue.
It absorbs instantly with an invisible finish, delivering biotin, marine silicium and gentle acids. Wear it on its own, or as the first step under your polish or treatment routine. This is a strengthening serum, not a polish.
Why people love it
- Strengthens the nail's keratin structure, right where weak nails need it most
- Builds strength without over-hardening, so nails stay flexible, not brittle
- Helps soft, bendy nails grow longer with less splitting
- Absorbs in seconds with an invisible finish, so you can wear it bare or under polish
- Locks in moisture
- No formaldehyde
- Made for nails left fragile by gel, acrylic or nail glue
Orders ship from our Melbourne warehouse within 1–2 business days (excluding sale periods) via Australia Post. New Zealand orders ship from our Auckland warehouse.
- AU Standard: $5.00. Estimated 2–8 business days.
- AU Express: $10.00. Estimated 1–4 business days.
- New Zealand: NZD $6. Estimated 1-2 business days.
- USA: USD $8.50, or free on orders USD $85+. Estimated 6–9 business days.
- Everywhere else: AUD $16 on all orders. Estimated 6–9 business days.
Returns: You can return eligible full-priced products within 60 days of receiving your order for a refund. Read more here.
Free SHIPPING on orders over $75
dispatched in 24 hours
60 day returns
Over 22,000+ 5-star reviews
Phaeodactylum Tricornutum Extract
Gluconolactone
AHAs
Tocopherol
FAQs
A hardener makes the nail harder, often with a high concentration of hardening agents, which can tip nails into brittle, and brittle nails snap. A strengthener conditions and supports the nail so it becomes more resilient and flexible. Nail Strengthener is a strengthener: it builds strength while keeping nails flexible, which is what lets them grow without breaking.
Anyone with thin, soft, bendy or short nails that struggle to grow. It is especially good for nails left weak and fragile after gel, acrylic or nail glue.
Apply two coats to clean, dry nails, 30 seconds apart, and let it dry. Do this daily for two weeks. It absorbs invisibly, so you can wear it on its own or as the first step under polish or your treatment system.
No. That is the whole difference between a strengthener and a harsh hardener. This formula strengthens while keeping nails flexible, and it contains no formaldehyde. If your nails ever feel over-hard, ease off the frequency and keep up your cuticle oil.
No. It strengthens without formaldehyde or formaldehyde-releasing ingredients.
Yes. It is designed to go on first, on bare nails, and absorbs in seconds with an invisible finish. Apply your polish or leave-on treatment over the top once it has dried.
Nails should start to feel firmer within the first week or two of twice-daily use. Lasting strength then builds as healthier nail grows out, which takes a few months, so the longer you stay consistent, the better the result.
Yes. Every Kester Black product is vegan and cruelty-free.
OUR GUARANTEE
We create products to be loved — every day, and for the long run.
If you’re not completely happy with your purchase, you can return it within 60 days of receiving your order.
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