In this deep dive
Plating is a metal film measured in microns, sitting on a body measured in millimetres. It does not fade and it does not last forever: it thins, and it thins fastest at the points that touch the world first. Every durability question is really a question about how fast that thinning reaches the base metal.
Structure
A film measured in microns
The body of a pin or a coin is millimetres thick. The finish on top of it is microns — a fraction of a hair. That ratio is the whole subject: the part will outlive its finish by a wide margin, and the finish is what the buyer sees.
The stack is built in order. Nickel goes on first, because it bonds to brass and to zinc alloy, adds a hard layer under the colour, and blocks diffusion between the base metal and the surface. The decorative layer goes on top of that: gold, silver, black nickel, rose gold. On some finishes a clear coat follows, to take the handling instead of the metal.
This is why “it is only plated” is a misleading phrase. A plated part is a metal object wearing a thinner metal skin, and the skin is doing three jobs at once: colour, corrosion resistance, and a hard surface for handling.
Finishes
What each finish promises
A finish is not a colour. It is a colour plus a gloss plus a texture, and the last two decide whether wear is visible at all. A bright gold and a satin gold can come from the same bath and age completely differently, because one reflects every scratch and the other scatters the light that would reveal it.
| Finish | What it looks like | How it wears | Care |
|---|---|---|---|
| Bright gold | Mirror polish, warm yellow | Dulls first, then shows fine scratches; breakthrough appears at the rim | Wipe only — polishing removes the layer you are trying to keep |
| Bright silver | Cool white, high reflectivity | Scratches read clearly; fingerprints tarnish first | Dry cloth; never silver dip |
| Satin / matte | Low gloss, soft sheen | Hides scratches, holds oil; repeated wiping polishes it smooth | Mild soap, dry immediately |
| Antique brass / copper | Darkened recess, bright high points | The darkening wears off the high points before the plating does | No abrasives — the patina is the design |
| Black nickel | Deep grey-black, low warmth | Wears to a lighter tone at the edges, where the contrast shows most | Avoid abrasion; a clear coat helps |
| Rose gold | Warm pink, copper-rich | Can darken with sweat; benefits most from a coat | Remove before swimming |
| Two-tone | Two finishes on one part | Wear at the boundary and on the higher tone | Check both finishes, not just the dominant one |
The practical rule: the glossier the finish, the more honest it is about wear. A satin surface hides scratches for a year and then looks uniformly tired; a mirror surface tells you about every contact from the first week. Neither is more durable — one is simply more talkative.
Failure
Four ways a finish dies
Finishes rarely fail for one reason. They fail in a sequence, and the sequence usually starts with something mechanical that lets the chemistry in.
Abrasion
Fabric, skin, keys in a pocket, other pins in the same bag. The finish is rubbed away a little at a time, always at the highest point first.
Corrosion
Chloride from sweat and sea air attacks the layer. Once a scratch exposes the base metal, the two metals form a couple and the corrosion accelerates at the edge of the damage.
Chemical attack
Perfume, sunscreen, chlorine and hair products sit on the surface and eat into the finish. It usually starts as a haze or a patch rather than a scratch.
Mechanical damage
A drop, a bend, a clutch clipped on too hard. The damage is a crack or a lifted edge, and corrosion follows it.
The finish reads even under raking light.
Visible only at an angle. The colour is still complete.
The layer beneath the colour shows at a high point.
Base metal reacts; the spot darkens and spreads.
Read that sequence backwards and it becomes a maintenance plan: everything you do to delay the second stage delays all three that follow.
Location
Where it goes first
Wear is not evenly distributed, and it is not random. It follows the geometry: the highest point touches the most things, so the highest point loses its finish first. On a pin, that means four predictable places.
The enamel method changes the map slightly. On soft enamel the raised lines are the high points, so they brighten and round first while the colour below them stays protected. On hard enamel the polished face is the high point, so wear arrives as a broad dulling across the field and a haze of fine scratches — less localised, and easier to see on a dark colour than on a light one.
The reverse deserves its own sentence. It is the face that rubs against clothing, and the clutch is the part that fingers work every time the pin is put on. Neither is visible in a product photograph, and both are usually the first place a plated layer gives up.
Distribution
Thickness is not uniform
A plating tank does not deposit an even film. Metal ions move with the current, and current concentrates where the geometry points at the anode: edges, corners, the tips of a star. Recesses and shielded areas sit in a lower field and receive less. The result is a coating that is thickest exactly where the part is most exposed, and thinnest where it is hardest to reach.
Three consequences follow. First, “thicker plating” is not a specification unless it names where it was measured — a part can be generous at the rim and thin in the field. Second, the nickel layer matters more than the colour layer for corrosion: a thick colour over a thin barrier still fails from beneath. Third, thicker is not free — a heavier deposit rounds fine detail and shifts the colour slightly, which is a real trade on a design that depends on hairlines.
Our workshop
What we control
Durability is decided by five things that happen before the part is packed, and none of them are visible in a finished photograph.
Nickel before colour
The nickel layer is adhesion and a diffusion barrier. A colour layer over zinc alloy without it corrodes from beneath, however thick the colour is.
Racking that does not starve the edges
Parts are positioned so current reaches the edges. Where the geometry demands it, they are re-racked for a second pass rather than accepted with thin rims.
Thickness measured, not assumed
Checked on a coupon from the same batch, not read off the rectifier setting. The number that matters is the one measured on metal.
A clear coat where it belongs
Antique and matte finishes get a coat; bright finishes may not. The coat protects against handling, and it wears too — it is a delay, not a shield.
Adhesion and salt spray, recorded per batch
Cross-hatch and tape for adhesion, neutral salt spray for corrosion. The result is kept with the batch record so a later question has an answer.
Salt spray: reference, not a promise
Neutral salt spray to ASTM B117 — neutral salt spray is the usual way to compare finishes. The figures usually quoted —24 / 48 / 72 hours — are reference points rather than a guarantee. What applies to a specific order depends on the finish and on the specification agreed for it.
The point of testing is not the certificate. It is that a batch with a number attached can be compared with the batch before it, and a complaint six months later can be answered with a record instead of an opinion.
Maintenance
Care that works, care that doesn't
Care is not about polishing a piece back to new. It is about keeping the second stage of the sequence — the micro-scratches — from arriving early. Most of the damage done to plated parts is done by people trying to clean them.
That helps
- Wipe with a dry microfibre cloth after handling — the oils on skin are the start of most tarnish.
- Store dry and separate; a small bag per piece stops parts scratching each other.
- Remove before swimming, showering, or a workout.
- Let the piece dry fully before it goes back in a box.
- Apply perfume and sunscreen first, then put the piece on.
That damages
- Toothpaste — it is a fine abrasive and it takes the finish with the tarnish.
- Silver dip and thiourea products — they attack the colour layer, not just the tarnish.
- Ultrasonic baths — they can lift a clear coat and open the edge of a plated layer.
- Chlorine, bleach and ammonia-based cleaners.
- Storing in a humid box, a bathroom, or a sealed bag with moisture inside.
One distinction worth keeping: on an antique finish, the dark recess is the design, and the high points are meant to brighten with handling. That is patina, not wear. On a bright finish, the same brightening is the first stage of loss. The finish tells you which one you are looking at.
Judgement
Wear or defect?
This is the only question that matters when a complaint is raised, and it has a clean answer: wear follows use, defects do not. A finish that has thinned where the part is handled is doing what physics says it must. A finish that blisters inside a recess nobody touches has failed as a process.
Wear
- Follows the high points — rim, raised lines, the face on a hard enamel part.
- Uniform in direction, and gradual over months of use.
- The colour thins and dulls; it does not lift in sheets.
- No blistering, and nothing spreading from a single point.
Defect
- Blistering, or a finish that peels in sheets.
- Pitting or corrosion inside recesses, where nothing rubs.
- Patchy discoloration within weeks of delivery.
- Corrosion spreading from one point on a part that has barely been worn.
If a claim is being made, three photographs settle most of it: a raking-light shot of the whole part, a macro of the affected edge, and a shot of the batch label. Re-plating a small part is rarely worth the handling; the honest answer is usually a remake, and the useful question is which batch it came from.