Nail Composition: What the Nail Plate Is Actually Made Of

Keratin: A Family of Proteins, Not One Substance

Keratin is often referred to as though it were a single material, but it is more accurate to describe it as a family of structural proteins. Different types of keratin are produced in different tissues throughout the body — skin, hair, and nails all rely on keratin, but not the same keratin. The nail plate is built specifically from hard α-keratin, the same category of dense, tightly structured keratin found in hair, which is notably different from the softer keratin found in skin.

This keratin is produced by keratinocytes — the cells responsible for keratin production — during the process described in detail on the Keratinisation Process page. Once this process is complete and the resulting onychocytes have become part of the visible nail plate, the keratin within them is no longer part of a living, active cell — it exists purely as structural material. This is why the nail plate can be described as built from keratin without being, itself, a living tissue.

Keratin forms the structural framework of the nail plate in the most literal sense: nearly everything else about how the plate behaves — its rigidity, its resistance to bending, its response to filing — traces back to how this keratin framework is built and held together.

Where Keratin Comes From: Amino Acids

Keratin itself is not a starting material — it is built from smaller building blocks called amino acids, assembled into long protein chains. A technician does not need a chemistry background to understand this, but knowing where keratin comes from helps explain why the nail plate behaves the way it does.

A small number of amino acids matter most to this structure. Cysteine is the most significant, because of what it makes possible structurally — this is covered in the next section. Methionine, glycine, and serine are also present in meaningful quantities and contribute to the overall protein structure. None of these amino acids are unique to nails; what matters is how they are assembled and, in cysteine’s case, how they connect to one another once assembled.

Disulphide Bonds and Structural Rigidity

Cysteine contains sulphur, and this single detail is central to why the nail plate is rigid rather than soft. Where two cysteine units end up positioned near each other within the keratin structure, their sulphur atoms can form a chemical bond with one another — a disulphide bond. These bonds act as cross-links, joining separate sections of keratin protein together rather than leaving them as loose, independent strands.

The more densely these cross-links occur, the more rigid and resistant to deformation the resulting structure becomes. This is the same underlying mechanism responsible for hair’s strength, and it is the primary reason the nail plate resists bending and stretching far more effectively than tissues without this level of cross-linking.

Water Content and Hydration

Water is not a fixed, static component of the nail plate — it moves continuously into and out of the plate, influenced by the surrounding environment, exposure to water or solvents, and individual factors. The exact water content varies considerably between individuals and circumstances; the specific ranges are covered on the Nail Plate page.

This continuous movement matters because hydration level temporarily changes how the nail plate behaves under force. Increased hydration is generally associated with increased flexibility, while dehydration is generally associated with reduced flexibility. These are general tendencies rather than fixed rules, and the practical implications for how nails and enhancement materials respond to force are explored further on the Nail Material Science page.

Lipids

Lipids make up only a small proportion of the nail plate’s overall composition — far less than in skin, where a lipid-rich outer barrier plays a much larger structural role. Within the nail plate, lipids are located between the cells rather than within them, sitting alongside the intercellular material that holds onychocytes together.

Despite the small proportion involved, this lipid content still has a measurable job to do. It influences how moisture moves through the plate, and it contributes to cohesion between neighbouring cells — helping the layered structure hold together as a unit rather than as loosely stacked material.

Trace Minerals

Trace amounts of minerals — including calcium, zinc, iron, and magnesium — can be detected within nail tissue. Their presence is well documented and not in dispute. What matters is what that presence does and does not mean.

Detecting a mineral within a tissue is not the same as that mineral being responsible for the tissue’s structural properties. In the nail plate, these minerals are present in quantities far too small to account for its hardness or rigidity — that structural role belongs to the keratin framework and its disulphide cross-linking, described above.

Common Misconceptions

A number of persistent beliefs about nail composition do not hold up against what the nail plate is actually made of and how it actually behaves.

This distinction matters for how technicians discuss nail health with clients. A client asking whether a supplement or protein-enriched product will make their nails stronger is really asking a question about structure and keratin condition, not about composition alone — and the honest answer is usually more nuanced than a single ingredient can address.

Composition vs Structure

Composition and structure answer two different questions, and conflating them is one of the most common sources of confusion in nail education. Composition answers: what is the nail made of? Structure answers: how are those materials organised?

Two nails can have almost identical chemical composition — similar keratin content, similar water content, similar trace minerals — and still behave very differently in practice. The difference comes down to factors that composition alone does not capture: thickness, architecture, hydration at a given moment, growth direction, porosity, and how the plate’s layers are organised.

This is why two clients can be told, correctly, that their nails are “made of the same thing” and still need entirely different approaches to product selection and service planning. Composition is the starting material; structure is what determines how that material actually performs.

Composition Is Not the Whole Story

Knowing what the nail plate is made of explains a great deal, but it does not, by itself, predict how a specific nail will behave under force. Composition alone cannot predict flexibility, brittleness, resistance to cracking, or how well a nail will support an enhancement — those outcomes depend on multiple interacting factors working together, not on chemical makeup in isolation. This is explored in more depth on the Nail Material Science page, which covers how nails and enhancement materials actually respond when force is applied.

In other words, composition tells you what a nail is built from. It does not, on its own, tell you how strong that particular nail will be — structure and condition matter just as much.

Key Facts

Frequently Asked Questions