In this article about nail care products, you will learn about the nail structure, various types of nail care products, their formulation, common ingredients, and how they work. Additionally, the article will cover the regulation and claims associated with nail care products. Historically, nails have been used to display social status for centuries. Today, trends have developed and continue to grow in the western world. Moreover, nails have become a way of self-expression that brings people together. Consequently, the cosmetics industry ensures that these products are suitable for consumer needs and regulated to ensure consumer safety.
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Nail Physiology
The nail unit includes the hardened plates of keratin known as the ‘nail’ and its surrounding tissue. Specifically, the nail unit makes up the distal and dorsal surface of the fingers and toes. The structure of the nail unit consists of several key components: the nail plate, nail bed, matrix, cuticle, and nail folds. The nail plate is the visible part of the nail, while the nail bed lies beneath it, providing nourishment and support. The matrix, located under the cuticle, is responsible for producing new nail cells, which push the older cells forward to form the nail plate. The cuticle acts as a protective barrier against infections, and the nail folds are the skin ridges that frame and support the nail on three sides.
Moreover, nails are a skin appendage similar to hair, sweat glands, and sebaceous glands, all of which make up the integumentary system. This system plays a crucial role in protecting the body from environmental damage, regulating temperature, and providing sensory information. Consequently, the health of nails can often reflect the overall health of an individual, as changes in nail appearance can indicate nutritional deficiencies, infections, or systemic conditions. Therefore, understanding the structure and function of the nail unit is essential for both cosmetic and medical purposes.
The Nail Unit
Free-edge
Distal-most part of the nail that grows beyond the digit. Appears white as it grows out because it is no longer attached to the nail bed.
nail plate
Hard, visible portion of the nail that attaches to the nail bed. It’s made up of dead keratinocytes that are translucent. The plate can be divided into three layers: dorsal, intermediate and ventral layers.
Nail root
Proximal portion of the nail that is hidden beneath the skin.
Nail germinal matrix
The germinal matrix sits behind the nail’s root. It causes most of the nail’s growth by creating new cells that migrate forward. Cells flatten and lose their nuclei as they migrate.
Lunula
The lunula is the most distal part of the germinal matrix. The name means ‘little moon’ in latin. Some peoples’ lunula is visible, whereas others’ aren’t, it is most commonly visible on the thumbs. The reason it is visible is because the germinal matrix is not transparent (unlike the nail plate), so it’s noticeable as an opaque white-ish portion at the least distal portion of the nail.
Sterile matrix (nail bed)
Found between the germinal matrix and hyponychium. Its function is to anchor the nail plate. This is where the dermis and epidermis of the nail bed form into longitudinal ridges to keep the nail in place.
Proximal fold
This is the fold of skin along the proximal region (base) of the nail plate.
Lateral folds
The fold of skin along the sides of the nail plate.
Hyponychium
Found below the nail’s free edge and distal to the nail bed. Its function is to seal out germs and it is rich in white blood cells.
Paronychium
This is the tissue found along the border of the nail at the lateral folds.
Eponychium
This is the tissue found along the proximal fold. It’s living tissue that produces the cuticle.
Perionychium
The tissue all around the nail. Includes the paronychium, eponychium, hyponychium, proximal & lateral folds and the nail bed/matrix.
Cuticle
Thin, dead and transparent layer produced by the eponychium. The cuticle extends onto the proximal portion of the nail plate. Its function is to protect the germinal matrix.
Nail Function
Sensory Assistance
Nails enhance the sensitivity of the fingertips, aiding in the perception of fine touch and subtle pressure changes. When you touch or feel an object, the presence of nails helps you detect textures and small variations on surfaces more accurately.
Tool Functionality
Nails act as natural tools, assisting in various everyday tasks that require precision and dexterity. They are used for tasks like scratching an itch, peeling stickers or labels, picking up small objects, and opening packages.
Ornamental
Nails serve a cosmetic function, allowing for decoration and personal expression through various nail art and manicure techniques. Many people paint their nails with nail polish, apply decorative nail art, or get manicures to enhance their appearance and express their style.
Protection
Nails protect the sensitive tips of fingers and toes from physical damage and injury. They act as a barrier against impacts, preventing direct trauma to the delicate skin and underlying tissues of the fingertips and toes.
Nail Care Product Types
Nail Varnish
The history of nail polish dates back to ancient China, where it was originally worn by rulers and high society members as a symbol of wealth and power. Initially, early formulations included a mixture of beeswax, gelatin, and egg white, dyed with orchids or roses. This mixture was applied to the nails and left for several hours to create a stain. Furthermore, popular colours mentioned in ancient manuscripts included reds and blacks, often enhanced with metallic dust of silver and gold. Consequently, stained nails were such a strong symbol of status that it was a crime for anyone outside the elite to wear them.
Today, nails also speak of social status. In many cultures, long nails symbolise people who do not belong to the working class (as you cannot have long nails for certain jobs). Even some men will grow out their nails on their pinkies to symbolise their status.
The formulations of nail varnishes are very different to those in ancient China though. Today, nail varnishes are made up of long-chain polymers suspended in solvents with colourants. They contain film-formers which sit on the surface of the nail and aren’t easily removed.
Water-based Nail Varnish
Nail varnishes do have their health concerns, especially as they contain solvents which need to be handled with care. With the growth of cosmetics marketed to children (below 16 years old), the ‘reasonable and foreseeable use’ of nail varnishes changes based on the demographic. The solvents used (such as butyl acetate & ethyl acetate) in traditional nail-varnishes are considered unsuitable for children who are likely to apply the nail varnish all over their fingertips and potentially expose themselves to large amounts of the product.
Water-based nail varnishes help to resolve this problem. They are formulated without potentially harmful solvents and replace them with water. This makes these products much more suitable for children, although adult supervision is still necessary.
Nail/Cuticle Oil
Nail and cuticle oils are used to soften the perionychium (tissue surrounding the nails) and cuticle. When applying nail varnish the cuticle can interfere with the nail varnish being laid down (by growing and lifting from beneath), so it is often softened and manually removed before nail varnishes are applied.
The perionychium can be slightly damaged during a nail-treatment (from pushing back the nail cuticles and filing the free edge and nail plate), so a nail oil can often help to soften and soothe any potential damage as well as providing a pleasant sensory experience.
Ingredients in Nail Care Products
Alcohol in nail care products
The solvent mixture includes alcohol, which helps dissolve the other ingredients in the formulation. Because ethanol is relatively volatile (easily evaporated) and affordable, manufacturers commonly use it in nail varnishes. Additionally, they often use alcohol-denat in nail polish removers because, as mentioned earlier, it dissolves polymers and makes them easily removable from the nail.
Solvents in nail care products
Other solvents such as butyl acetate and ethyl acetate are highly volatile. They are capable of dissolving large polymers quickly but also dry very quickly. They provide an even dispersion of pigments across the nail varnish, and the low-viscosity makes it easy to apply. These solvents do have a potent smell and can cause headaches, therefore, it’s recommended to apply nail varnish in a well ventilated room.
Butyl acetate ^
Resins & polymers in nail care products
Resins and polymers are the components which remain on the nail when the solvents have evaporated. They are long-chained and keep the pigments locked-in on the surface of the nail. The most common film-forming polymer is nitrocellulose.
Nitrocellulose ^
Plasticisers in nail care products
Plasticisers ensure that the nail varnishes are not too brittle, but they also help with the application, durability and adhesion of nail varnishes onto the nail plate. They ensure that the film formers are not too brittle, otherwise the product would easily crack and chip.
Formulation of Nail Care Products
Nail Varnish
Ingredient | Maximum Concentration (% w/w) |
Ethanol (alcohol, alcohol denat., isopropyl alcohol) | 90 |
Solvents | 90 |
Resins, polymers | 50 |
Plasticisers | 15 |
Colourants | 15 |
Thickeners | 5 |
UV filters | 2 |
Ethanol – 90%
Alcohols act as solvents to dissolve other ingredients, help in quick drying, and ensure even application. Examples: alcohol, alcohol denat. Isopropyl alcohol.
Solvents – 90%
Solvents dissolve the film-forming agents, pigments, and other components, facilitating smooth application and quick drying. Examples: ethyl acetate, butyl acetate, toluene.
Resins, Polymers – 50%
These ingredients form the durable, shiny film on the nail and provide adhesion and flexibility. Examples: nitrocellulose, acrylates copolymer.
Plasticisers – 15%
Plasticisers make the nail varnish flexible and prevent it from becoming brittle. Examples: dibutyl phthalate (DBP), camphor, triphenyl phosphate.
Colourants – 15%
Colourants provide the desired colour and opacity to the nail varnish. Examples: CI 15850 (Red 6 Lake), CI 77499 (Iron Oxides), Mica
Thickeners – 5%
Thickeners adjust the viscosity of the nail varnish, ensuring it is neither too runny nor too thick. Examples: stearalkonium hectorite, hydroxyethylcellulose
UV Filters – 2%
UV filters protect the nail varnish from discoloration and degradation due to UV exposure. Examples: benzophenone-1, ethylhexyl methoxycinnamate.
Water-based Nail Varnish
Ingredient | Maximum Concentration (% w/w) |
Resins, polymers | 90 |
Plasticisers | 20 |
Colourants | 15 |
Thickeners | 15 |
Additional ingredients | 10 |
Preservatives | 1 |
Water | To 100 |
Resins, Polymers – 90%
These form the main film on the nail, providing adhesion, durability, and a smooth finish. Examples: acrylic polymer emulsions, polyurethane dispersions, styrene/acrylates copolymer.
Plasticisers – 20%
Plasticisers impart flexibility to the nail polish film, preventing it from becoming brittle and cracking. Examples: dipropylene glycol dibenzoate, triethyl citrate.
Colourants – 15%
Description: Colourants give the nail polish its colour and opacity. Examples: CI 77499 (iron oxides), CI 15850 (red 7 lake), titanium dioxide.
Thickeners – 15%
Thickeners control the viscosity of the nail polish, ensuring it applies smoothly without being too runny or too thick.Examples: hydroxyethylcellulose, xanthan gum, acrylates copolymer.
Additional Ingredients – Maximum Concentration: 10%
Description: These can include various functional ingredients like UV stabilisers, adhesion promoters, and gloss enhancers. Benzophenone-4, Trimethylsiloxysilicate, Polysilicone-11.
Preservatives – 1%
Preservatives prevent microbial growth and ensure the product remains safe and effective during its shelf life. Examples: phenoxyethanol, ethylhexylglycerin, sodium benzoate.
Water – To 100%
Description: Water acts as the primary solvent in water-based nail varnish, dissolving other ingredients and forming the base of the formulation.
Nail Conditioner
Ingredient | Maximum Concentration (% w/w) |
Unsaturated fatty acids, proteins, vitamins | 10 |
Colourants | 1 |
Parfum | 1 |
Antioxidants | 0.5 |
Preservatives | 0.5 |
Oils | To 100 |
Unsaturated Fatty Acids, Proteins, Vitamins – Maximum Concentration: 10%
These ingredients nourish, strengthen, and condition the nails, promoting health and resilience. Examples: linoleic acid, oleic acid, Hydrolyzed Wheat Protein, Vitamin E (Tocopherol), Vitamin B5 (Panthenol).
Colourants – 1%
Colourants are used to give the nail conditioner a visually appealing colour or to tint the product. Examples: CI 19140 (Yellow 5), CI 42090 (Blue 1).
Parfum (Fragrance) – 1%
Fragrances are added to enhance the sensory experience by providing a pleasant scent to the product. Examples: Essential Oils, Synthetic Fragrances.
Antioxidants – Maximum Concentration: 0.5%
Antioxidants prevent the oxidation of other ingredients, thereby extending the shelf life and effectiveness of the product. Examples: Tocopherol (Vitamin E), Ascorbyl Palmitate, Butylated Hydroxytoluene (BHT).
Preservatives – 0.5%
Preservatives inhibit the growth of microorganisms, ensuring the product remains safe and free from contamination. Examples: Phenoxyethanol, Ethylhexylglycerin, Sodium Benzoate.
Oils – To 100%
Oils act as the base and primary carrier for other ingredients, providing hydration, nourishment, and a smooth application. Examples: Jojoba Oil, Sweet Almond Oil, Argan Oil.
Nail Glue
Ingredient | Maximum Concentration |
Adhesive (acrylates) | To 100 |
Adhesive (Acrylates) – To 100%
Acrylates are used as film-forming agents that provide adhesion, flexibility, and durability to the nail glues. Examples: Acrylates Copolymer, Acrylic Acid, Methacrylic Acid, Ethyl Cyanoacrylate, Polymethyl Methacrylate (PMMA).
Regulations of Nail Care Products
CLP Labelling
The CLP Regulation (CE) 1272/2008 aligns previous EU legislation with the GHS (Globally Harmonised System of Classification and Labelling of Chemicals), a United Nations system to identify hazardous chemicals and to inform users about these hazards. Additionally, it also has links to the REACH legislation. This only applies to substances which are classified as potentially hazardous.
Finished cosmetic products are exempt from the requirements of the CLP Regulation and do not need to display CLP hazard symbols and warnings. If a finished cosmetic product is flammable, the Responsible Person may choose to include flammability labelling on a voluntary basis. Cosmetics Europe (CE), the European personal care association, has published industry recommendations for voluntary labelling. However, these recommendations do not specify the details of the logo and writing characteristics, leaving the decision to apply voluntary labelling up to the individual company.
Notification
When nail varnish products are being uploaded to notification portals, it’s important to note if there are any reportable ingredients that the authorities need to know about.
For the SCPN (submit cosmetic product notifications) in the UK, they have a list of NPIS (national poisons information service), which includes a list of reportable ingredients. Notably, butyl acetate and ethyl acetate are featured on this list and must be reported if the concentration of these ingredients exceeds 1%, which nail varnish products often do.
regulatory updates
The use of plasticisers in nail polishes has sparked some controversy over the years. The EU banned dibutyl phthalate (DBP), once a widely used plasticizer, in 2004 due to concerns about its potential to interfere with the human hormone system. The US has also phased it out. Manufacturers have since introduced alternatives such as camphor, glyceryl tribenzoate, and triphenylphosphate (TPPP). However, TPPP, a common replacement for DBP, has also raised concerns about hormone disruption. This highlights the challenges in finding safe replacements for banned cosmetic ingredients.
Claims of Nail Care Products
Non-permitted claims
Anti-fungal
Any claims which insinuate a reduction or treatment of bacteria, fungi or viruses are not cosmetic claims. Anti-fungal nail varnishes are classified as biocidal products and fall under the biocides regulations. However, companies may classify anti-fungal products as cosmetics (especially if they contain pigments) if they present and distribute them as such. This means that an anti-fungal product can be both a cosmetic and a biocide, requiring compliance with all the regulatory needs of both categories.
Anti-bite
Anti-bite nail varnishes are marketed as products intended to have a poor taste to deter consumers from biting their nails, however, this is a very borderline claim as ‘taste’ is not a function of a cosmetic product as described by the eu cosmetic definition.
“any substance or mixture intended to be placed in contact with the external parts of the human body (epidermis, hair system, nails, lips and external genital organs) or with the teeth and the mucous membranes of the oral cavity with a view exclusively or mainly to cleaning them, perfuming them, changing their appearance, protecting them, keeping them in good condition or correcting body odours.”
It can be argued that any nail varnish is an anti-bite nail varnish as consumers should know that biting on nail varnish is potentially damaging to their health. I would advise to steer clear of anti-bite claims.
Non-toxic
Nail varnishes have a reputation of being ‘toxic’ because they contain potentially hazardous ingredients. This has led consumers to seek out alternatives to the traditional ‘toxic’ nail varnish – giving rise to the ‘non-toxic’ ‘clean beauty’ trend.
Calling a product ‘non-toxic’ denigrates other products on the market, insinuating that the other products are toxic, but they are not. All cosmetic products placed on the market have a safety assessment which outlines the nature of the product and its safety under usual and foreseeable use.
Permitted claims
Strengthening
Strengthening claims are permitted and easily substantiated. The strength of nails is highly dependent on the integrity of the nail plate. If the nail plate has an additional coating, it will help strengthen the nails and prevent breakage to some degree. There are specific nail polishes which contain a large proportion of plasticisers which help bend with the nail slightly whilst retaining a sturdy base.
Fast-drying
Fast-drying claims are substantiated by a higher proportion of highly volatile solvents. The more volatile the solvent, the faster the nail varnish will dry. However, there are formulation issues when the proportion of fast-drying solvent is too high. The brush used to apply the nail varnish is likely to dry out faster and leave residue around the bottleneck – and if the lid is left off the bottle for too long, the whole nail varnish could be affected.
Long-lasting & chip-proof
The main issue with traditional nail varnishes is that they chip easily and can come off whilst performing tasks like washing the dishes. Nail varnishes can be strengthened by adding the right amount of plasticisers to reduce the brittle nature of nail varnishes and help adhere the product to the nails.
