Prepare the nail
Clean, dry nail, with old polish removed using an acetone-free remover.
Your concern
Clear nail polish: base coat, top coat or treatment polish, which one should you choose?
A clear polish can protect, add shine, strengthen or simply make your colour last. But you still have to pick the right one. Here is what base coats, top coats and treatment polishes are for, how to apply them so they last, what Europe bans in nail polish, and the precautions dermatologists point out.
By Maria Dagiel-Petit, Managing Director of Belweder France · 7 November 2026
Base coat, top coat, treatment polish: each has its own role
The base coat goes on first, directly on the nail. Test-Achats, the Belgian consumer association, explains that it smooths the surface and protects the nail from the discolouration and drying that coloured polishes can cause. Dermato-Info, the website of the French Society of Dermatology (SFD), also recommends applying a base coat before colour.
The top coat goes on last. It seals the colour, adds shine and, according to Test-Achats, makes the polish last longer, just like the base coat. A clear polish can also be worn on its own, for a natural, well-groomed look: it is the choice for short nails, working hands, or anyone who simply wants a neat finish.
Treatment polishes go further, with actives designed for fragile nails. Our ultra-glossy diamond powder polish strengthens and waterproofs the nail, with a mirror-like shine. Our keratin nail hardener creates a ‘bandage’ effect on soft, brittle nails. Our strengthening AHA treatment polish combines fruit acids and eight fruit extracts to gently strengthen the nail and limit dehydration. All three can be used as a base under colour or worn on their own.
How to apply clear nail polish properly
Polish lasts better when the nail is clean and dry. Remove old polish with an acetone-free remover, as Dermato-Info advises, wash your hands and wait until they are completely dry. Gently push back the cuticles without cutting them, and file your nails horizontally to stop them from peeling.
Then wipe the brush on the neck of the bottle so that only a small amount of polish is left. Apply a thin coat in three strokes: one in the centre, then one on each side. Let it dry, then apply a second coat. Two thin coats last better and dry faster than one thick coat, which stays soft and chips. Finally, run the brush along the edge of the nail to seal the polish.
Remember to take breaks too. Dermato-Info advises not keeping polish on for more than a few days in a row, and leaving the nail polish-free for 48 hours, moisturising it, before applying more. Test-Achats recommends using removers in a well-ventilated room. During these breaks, a treatment such as our panthenol wax nourishes the nail and cuticles. If your nails are fragile, our brittle and peeling nails guide sets out the routine to strengthen them.
Application in 3 steps
Apply two thin coats
Brush wiped on the neck of the bottle, a first coat, drying time, then a second.
Take a break
After a few days, remove the polish and let your nail breathe for 48 hours.
The strengthening AHA treatment polish on video
Strengthening AHA treatment polish for peeling, brittle, ridged nails
A clear polish with fruit acids that strengthens the nail plate of weakened nails and gives them a natural shine.
What European regulations ban
Nail polishes are cosmetics, subject to the European regulation governing their ingredients. Several once-common substances have been removed from them. Dibutyl phthalate (DBP), used to make the polish film more flexible, was assessed by the European scientific committee SCCNFP in 2004, then banned from cosmetics because of its classification as toxic to reproduction.
Toluene, a solvent, has been restricted since Directive 2009/6/EC: 25% maximum in nail products, with the warning ‘For adult use only’ and the requirement to keep the product out of reach of children. Formaldehyde, long used in hardeners, has been banned since Regulation (EU) 2019/831.
Semi-permanent gel polishes are the most affected by recent rules. Since 2021, Regulation (EU) 2020/1682 has restricted two acrylates, HEMA and di-HEMA TMHDC, to professional use, with the warning ‘Can cause an allergic reaction’. TPO, a photoinitiator that allows the polish to harden under the lamp, has been banned since 1 September 2025 by Regulation (EU) 2025/877, with no sell-through period, Service-public.fr points out. Finally, the NHS notes that even classic polishes and hardeners can cause contact eczema in sensitive people.
Gel polish: the precautions dermatologists recommend
Gel polish lasts for several weeks, but it comes at a cost to the nail. Dermato-Info does not recommend it: it contains allergenic acrylates, applying it involves buffing the nail, it can encourage germs, and it requires a UV lamp. Que Choisir describes acrylates as extremely sensitising substances.
France’s National Agency for the Safety of Medicines (ANSM) describes the possible allergies: eczema around the nails, but also on the eyelids or face, which we touch with our fingers. The agency recommends waiting about a month before a new application, to let the nail rest. If you still choose gel polish, have it applied by a professional, and remove it as soon as the skin around the nail turns red or itches.
For children, the answer is clear. The SFD and the French Society of Paediatric Dermatology advise against artificial nails before the age of 16, and an NHS hospital, the Queen Victoria Hospital, advises children to stick to ordinary polish. A clear polish, removed with a gentle remover such as our extra-gentle lavender and panthenol remover, remains the simplest option. For children who bite their nails, our nail biting guide offers other solutions.
Frequently asked questions
It can be used as a base coat under colour, as a top coat to make it shine and last, or worn on its own. Treatment polishes add actives to strengthen the nail.
The base coat goes on first to smooth and protect the nail. The top coat goes on last to seal the colour and make it last longer, explains Test-Achats.
Two thin coats, with drying time in between, last better than one thick coat.
Dermato-Info does not recommend it: it contains allergenic acrylates and applying it requires buffing the nail.
Ordinary polish, yes, with a gentle remover. Artificial nails, however, are not recommended before the age of 16 by the SFD and the SFDP.
Find out more: our guides to brittle and peeling nails, ridged nails and nail biting, and all our nail care products. Free delivery in France on orders of €39 or more.
Sources: Test-Achats, “Comment choisir votre vernis à ongles ?”, 27 January 2026; French Society of Dermatology, Dermato-Info, “L’ongle”, Dr Olivier Cogrel and Dr Léna Ronjat, updated 20 May 2025; Dermato-Info, “Connaître les causes de l’eczéma de contact”, Prof. Angèle Soria, updated 21 April 2025; SCCNFP, “Opinion concerning dibutylphthalate”, 2004; European Commission, “Directive 2009/6/EC”, 4 February 2009; European Commission, “Regulation (EU) 2019/831”; European Commission, “Regulation (EU) 2020/1682”; European Commission, “Regulation (EU) 2025/877”; Service-public.fr, “Vernis semi-permanents : une substance jugée toxique interdite d’utilisation”, 4 September 2025; NHS, “Contact dermatitis – Causes”; Que Choisir, “Faux ongles et vernis semi-permanents : une ribambelle d’effets sur la santé”, Fabienne Maleysson, 3 October 2025; ANSM, “Pose d’ongles artificiels : l’ANSM informe sur les risques et les précautions à prendre”, updated 5 March 2021; SFD and SFDP, “Instituts de beauté pour enfants : la SFD et la SFDP alertent”, 3 February 2025; NHS, Queen Victoria Hospital, “Experts warn of danger of acrylic nails on children”, December 2018.
Spotted a mistake or some information that needs updating? Write to us: we’ll check and correct the guide if necessary.