Does semi-permanent varnish damage the nails?

Having nails impeccably coloured and resistant to chipping is a dream for nail varnish enthusiasts. Semi-permanent versions are appealing for this as they withstand climatic variations, UV rays, humidity, and shocks. This manicure technique is performed with an acrylic gel introduced into a varnish that does not dry in open air but hardens when exposed to a UV or LED lamp. Specifically, a photopolymerisation reaction occurs within the semi-permanent varnish. The application of this type of varnish can be done at home or in a salon and takes about 30 to 45 minutes. The result then lasts for several weeks. Another advantage of semi-permanent varnishes is that their use is now widely democratised and they come in numerous versions. Semi-permanent varnishes thus present an interesting option for those seeking a long-lasting and resilient manicure.

Despite their numerous benefits, semi-permanent varnishes are not without consequences for nail health, particularly when used repeatedly or removed without caution.

Indeed, the unique formulation of semi-permanent nail varnishes, which is responsible for their durability, is not necessarily beneficial for the nails. As mentioned earlier, this type of varnish is composed of acrylic polymers and hardens under the action of UV or LED light through a photopolymerisation mechanism. However, by creating a solid and adherent layer, this reaction also forms a nearly hermetic barrier on the surface of the nail. Although it cannot be said that this prevents the nail from breathing — nails do not breathe in the literal sense as they are not the site of any gas exchange — this prolonged occlusion can lead to an increase in its moisture content, which makes it soft and fragile. Indeed, when the keratin of the nail absorbs too much water, it swells, which causes the layers that make up the nail to separate and potentially split. This problem, already posed by nail varnishes in general, is amplified by semi-permanent varnishes, which create a much stronger barrier.

Beyond their resilient texture, semi-permanent varnishes contain reactive molecules that can weaken the nails and surrounding skin. Among the commonly used molecules are methacrylates, such as hydroxyethyl methacrylate (HEMA), trimethylhexyl dicarbamate (DI-HEMA), and hydroxypropyl methacrylate (HPMA). These are essential to the photopolymerisation process but they are also known to be potentially irritating to the skin and nails, causing redness and itching.

Furthermore, the removal of semi-permanent nail varnish can also weaken the nails. Indeed, to remove a semi-permanent varnish, one must combine mechanical sanding with the use of acetone. However, while this molecule is effective in removing varnish, it also dissolves some of the protective lipids of the skin and nails. Additionally, when poorly executed, sanding can sometimes be too abrasive and damage the first layers of keratin, making the nail thinner and more susceptible to damage. This step can also create small ridges on the nail surface. That's why it is often recommended to entrust the removal of a semi-permanent varnish to a professional in a salon.

To limit the damage to nails caused by semi-permanent varnish, it is recommended to take breaks of about two weeks between each varnish application. In the meantime, take the opportunity to hydrate and nourish your nails, using a vegetable oil for example.

Note : The potential damage to nails is not the only concern raised by semi-permanent nail varnishes. Like traditional nail varnishes, some formulas may contain formaldehyde, dibutyl phthalate, or even parabens, all of which are suspected to be endocrine disruptors at high doses or with chronic use.