The chief stew books you a pedicure for a charter guest. You take off the old polish and find a thickened, yellow, crumbling big toenail that lifts away from the bed. She wants it painted red and she wants it now. The correct answer is not red polish, and knowing why is the difference between a technician and an amateur.
The Nail Unit
| Part | What it is |
|---|---|
| Nail plate | The visible hard keratin plate |
| Nail bed | The vascular skin beneath the plate; gives the pink colour |
| Matrix | The growth engine under the proximal fold — damage here damages the nail permanently |
| Lunula | The visible pale half-moon; the front of the matrix |
| Cuticle / eponychium | The eponychium is living tissue at the base; the cuticle is the thin dead layer stuck to the plate |
| Hyponychium | The seal under the free edge — a barrier against infection |
| Free edge | The part you shape |
The eponychium and hyponychium are seals, not untidiness. Cutting them breaks the body's barrier against infection. This single fact governs all cuticle work.
Growth
Fingernails grow roughly 3 mm per month, toenails around 1 mm — so a full fingernail takes about 6 months, a toenail up to 12–18. Growth slows with age, illness and poor circulation, and speeds slightly in warmth. It means two things: damage you cause takes months to grow out, and a horizontal ridge tells you something happened to that guest weeks ago.
Healthy vs Unhealthy
Healthy: smooth, translucent pink plate, intact seals, no separation, no pain, no odour, no discolouration. Unhealthy: separation from the bed, thickening, crumbling, green or black discolouration, swelling, heat, pus, pain.
Treat or Refer
| Condition | What it is | Action |
|---|---|---|
| Longitudinal ridges | Age-related | Treat; buff lightly |
| Beau's lines | Horizontal grooves from illness or trauma | Treat cosmetically |
| Leuconychia | White spots, usually minor trauma | Treat |
| Brittle / peeling nails | Dryness, over-exposure to solvent | Treat; oil and hydrate |
| Hangnail | Torn skin at the fold | Trim the torn skin only |
| Onychomycosis | Fungal: thick, yellow, crumbling, lifting | Refer. Do not polish. Do not file |
| Paronychia | Infected nail fold: red, swollen, hot, pus | Refer. Do not touch |
| Onycholysis | Plate separating from bed | Refer |
| Pseudomonas ("greenies") | Green stain under an enhancement | Refer; remove enhancement, do not re-cover |
| Dark streak / new pigmented band | Could be many things, including serious | Refer to a doctor. Say nothing more |
| Ingrown toenail with infection | Red, swollen, discharging | Refer |
The rule: a cosmetic condition you may treat and improve. A medical condition — infection, inflammation, separation, unexplained pigment — you refer to a doctor. You never diagnose, and you never paint over a problem so it cannot be seen.
Onboard Notes
- The matrix makes the nail; damage there is permanent.
- The eponychium and hyponychium are infection seals. Do not cut them.
- Thick, yellow, lifting, green, hot, painful or oddly pigmented: refer.
- Polish over an infection hides it, feeds it, and is on you.
- Preparatory study only. Nothing here qualifies you to treat a guest. Beauty and nail work requires an accredited vocational qualification and professional insurance.