Electroplating in China: Chrome, Nickel, and Gold Finishes

Electroplating in China covers the full range of industrial finishes: decorative chrome, hard chrome, nickel, gold, zinc, copper, and more. Chinese plating shops handle everything from bathroom fittings and automotive trim to jewelry and electronic connectors, usually at lower cost than Western suppliers. The part most buyers get wrong is the specification. Writing "chrome plated" on a purchase order without naming the thickness in microns, the test method, and the compliance standard gets you whatever the shop finds convenient.

This guide explains how plating works, which finishes fit which products, what thickness to demand, and how to check that you received it. China remains a strong place to source plated parts, provided the spec is written correctly before production starts.

Many foreign buyers underestimate how much the plating process varies from shop to shop. Rack lines and barrel lines produce different uniformity, and pre-treatment quality decides whether a coating survives two years or peels in six months. A sourcing partner such as CN Ally can help identify plating suppliers whose lines and chemistry match your product's requirements, rather than choosing on quoted price alone.

How does electroplating actually work?

Electroplating deposits a thin metal layer onto a part using an electric current. The part goes into a chemical bath containing dissolved metal ions; the current pulls those ions out of solution and onto the part's surface. Thickness grows with time and current, which is why plating is measured in microns and specified as a range, not a single number.

The process is only as good as what happens before the current switches on. A plater cleans and degreases the part, often etches or activates the surface, and may strike it with a thin intermediate layer of copper or nickel. Then the main deposit goes on, followed by rinsing and sometimes a passivation topcoat.

Which finishes do Chinese plating shops typically offer?

No single finish excels at looks, corrosion protection, conductivity, and wear resistance all at once, so start from the problem you need solved.

Finish · What it does · Common uses · Notes for buyers

• Decorative chrome: Mirror-bright finish over nickel; thin chromium layer on top · Bathroom fittings, automotive trim, furniture hardware · The chrome itself is mostly cosmetic; the nickel underneath does the corrosion work
• Hard chrome: Thick, wear-resistant chromium deposit · Hydraulic rods, molds, industrial rollers · Functional, not decorative; heavy build-up, ground and polished after plating
• Nickel: Corrosion-resistant barrier layer; bright or matte · Undercoat for chrome and gold; standalone finish for hardware · Works as a barrier, not a sacrificial coating like zinc
• Gold: Corrosion resistance, conductivity, luxury appearance · Jewelry, connectors, electronic contacts · Expensive; decorative gold layers are typically only 1 to 5 microns thick
• Zinc: Sacrificial corrosion protection for steel · Fasteners, brackets, stamped steel parts · Usually paired with a chromate passivate; needs a sealer for serious salt-spray hours
• Copper: Conductivity; leveling base layer · PCBs, electronics, undercoat on steel and plastic · Often a strike or build-up layer rather than the final surface

Some shops also run silver, rhodium, tin, brass, or black nickel. Ask what baths are actually installed before assuming a capability exists. A shop that plates zinc for fasteners may not have a gold line.

Decorative plating vs functional plating: not the same product

Decorative chrome and hard chrome share a name and almost nothing else. Decorative chrome is a system: copper, then nickel, then a very thin flash of chromium, often under one micron. The mirror shine comes from the chrome, but the corrosion protection comes from the nickel underneath. If the nickel is too thin or porous, rust appears through pinholes no matter how shiny the chrome looks.

Hard chrome is the opposite. It builds up tens of microns of chromium for wear resistance on hydraulic shafts and tooling. It looks dull gray straight out of the tank and is usually ground afterward. Quoting "chrome plating" without saying which type is one of the most common specification errors buyers make with Chinese suppliers. Always name the system: decorative nickel-chrome or hard chrome, plus the thickness.

Why substrate prep decides whether plating survives

Adhesion is the property buyers test least and regret most. A plating layer bonds only as well as the surface it lands on. Rust, scale, oils, polishing compounds, and even fingerprints left on the part before plating become weak points where the coating later peels or blisters.

Professional shops run a defined pre-treatment sequence: alkaline degrease, acid activation or etch, and a copper or nickel strike on difficult substrates. Steel needs rust removal; die-cast zinc needs the right activation or the deposit will blister; ABS plastic needs etching plus a palladium catalyst and an electroless copper or nickel underlayer before it can take a current at all. When a supplier quotes fast turnaround, ask whether pre-treatment time is included or quietly skipped.

How thick should the plating be?

Thickness in microns is the single most important number on a plating specification. The finishing industry's Metal Finishing Guide for nickel-chromium coatings suggests 10 microns of nickel plus 0.1 microns of chromium for mild service conditions, and 15 to 20 microns of nickel plus 0.3 to 0.8 microns of chrome for moderate conditions (finishing.com). Mild conditions here mean indoor environments, not kitchens and bathrooms.

For other common systems, typical ranges are:

Application · Finish system · Typical thickness

• Decorative chrome, indoor: Nickel + chrome · 10 µm Ni + 0.1 µm Cr (mild service)
• Decorative chrome, moderate exposure: Nickel + chrome · 15–20 µm Ni + 0.3–0.8 µm Cr
• Gold plating, jewelry: Gold over nickel on brass · 1–5 µm gold
• Zinc on steel fasteners: Zinc + chromate passivate · 5–25 µm (ASTM B633 classes 5, 13, 25)
• Hard chrome, hydraulic shafts: Chromium · Tens of microns, per drawing

A few points to note. Decorative gold is genuinely thin: bath gold deposits about one micron in roughly five minutes, so building serious thickness takes real tank time. Thickness must be measured on significant surfaces, not hidden recesses where the current barely reaches. And "min" on a drawing means the thinnest acceptable point, not the average.

What salt-spray results should you expect?

Salt-spray testing accelerates corrosion in a fog chamber. The common test is neutral salt spray per ASTM B117 (or ISO 9227), reported in hours to white rust and hours to red rust. It is a comparison tool, not a calendar: 96 hours in a cabinet does not equal 96 days outdoors.

Expectations scale with the finish system. The nickel-chrome guide anticipates mild-service parts surviving about 8 hours in acetic salt spray, and moderate-service parts lasting 24 hours, or 4 hours in the more aggressive CASS test (ASTM B368). Zinc with a yellow chromate conversion coating typically reaches around 96 hours to white rust; zinc-nickel alloy systems can reach 500 hours or more. Higher numbers usually require sealers over the passivate, which is a separate step and a separate cost.

Specify the test standard, the duration, and whether you are judging white rust or red rust. "Passes salt spray" without those details means nothing on a purchase order.

RoHS, REACH, and hexavalent chrome: the compliance rules that matter

European buyers face two overlapping rule sets on plated parts. Getting them wrong can block a shipment at customs or trigger a recall.

RoHS (EU Directive 2011/65/EU) restricts hexavalent chromium, Cr(VI), to 0.1 percent by weight in each homogeneous material. Trivalent chromium, Cr(III), and metallic chromium are not restricted. Hard chrome plating deposits metallic chromium, so the finished coating does not contain hexavalent chrome and remains compliant. What is effectively banned is hexavalent chromate conversion coatings, the yellow chromates once standard on zinc plating. Chinese platers serving European customers have largely moved to trivalent chromium passivates.

REACH adds a second constraint for anything worn on the body. Annex XVII, Entry 27 limits nickel release to 0.5 micrograms per square centimeter per week for articles in direct and prolonged skin contact, such as earrings, necklaces, bracelets, rings, and watch straps (Nickel Institute). Pierced body parts face a stricter 0.2 limit. A gold flash over nickel on a bracelet does not automatically comply; the coating must keep nickel release under the limit for at least two years of normal wear.

China enforces its own environmental rules on plating shops, and wastewater treatment compliance is one reason prices vary so much between suppliers. A shop cutting corners on effluent treatment can quote far less than a compliant one. Ask suppliers how they handle wastewater, and treat an evasive answer as information.

What drives the cost of plating in China?

Plating quotes vary widely because several independent factors stack up:

• The metal itself. Gold price is the obvious one, but nickel and copper prices move too. A quote that seems fixed may assume today's metal prices, so ask how the supplier handles fluctuations on precious-metal finishes.
• Surface area and thickness. Plating cost scales with the area to cover and the microns to deposit. Doubling thickness roughly doubles tank time.
• Rack vs barrel. Barrel plating tumbles small parts in bulk and is cheap per piece; rack plating mounts each part individually for uniformity and costs more in labor. Small fasteners go in barrels; visible trim goes on racks.
• Pre-treatment and masking. Complex parts that need masking of threads or bores add labor. Dirty or rusty substrates need more prep.
• Volume and line utilization. Plating lines charge partly per rack or per barrel load. Small lots carry a setup charge that dominates the unit price.
• Testing and compliance. Salt-spray testing, XRF thickness checks, and compliance reports add cost. They also add the only evidence you have that the finish is what you ordered.

Common defects and what causes them

Defect · What you see · Usual cause

• Peeling / flaking: Coating lifts off in sheets or flakes · Poor pre-treatment or contamination before plating; the strike layer never bonded
• Blistering: Raised bubbles under the surface · Trapped gas or contamination, common on die-cast zinc with wrong activation
• Pitting: Small holes in the deposit · Air bubbles or particles clinging to the surface in the tank
• White rust: White powdery corrosion on zinc · Passivate too thin or sealer missing
• Red rust through chrome: Rust spots on shiny chrome · Nickel underlayer too thin or porous; chrome is porous by design
• Dull or cloudy gold: Matte patches on jewelry · Bath chemistry drift or current density too high

Most plating defects trace back to process control: shops that monitor bath chemistry, filter tanks, and rinse between steps avoid most of them.

QC tests worth specifying on your purchase order

You cannot inspect plating quality into existence after the parts ship, but you can make the acceptance criteria explicit before production:

• XRF thickness measurement. X-ray fluorescence reads coating thickness and composition without destroying the part. Specify minimum thickness on significant surfaces and who performs the measurement.
• Salt-spray testing. Name the standard (ASTM B117 or ISO 9227), the hours, and whether white rust or red rust is the failure criterion.
• Adhesion testing. A cross-hatch and tape test, or a bend test on a sample coupon, catches poor pre-treatment before thousands of parts are affected.
• Visual inspection under defined lighting. For decorative finishes, agree on what counts as acceptable: no pits, no blisters, no unplated areas on visible surfaces. Define the viewing distance and light.
• Nickel-release testing (jewelry). EN 1811 for EU-market plated jewelry and accessories.

Third-party quality control inspections before shipment are the practical way to verify these criteria when you cannot visit the plating line yourself.

How to vet a plating supplier in China

Plating is a process industry, so vetting means looking at the line, not the brochure. Useful questions include: which baths are installed and how the shop controls bath chemistry; whether it runs its own wastewater treatment; what thickness and salt-spray results it can document from recent jobs; and whether it will plate a first-article sample for your approval before the production run.

A factory audit that covers environmental compliance and process documentation is worth more here than in most product categories, because plating quality is invisible until it fails. Ask for references from buyers in your market who import similar finishes, and confirm the supplier understands your compliance requirements rather than simply nodding at them.

Frequently asked questions

Is chrome plating RoHS compliant?

The finished chrome coating is metallic chromium, which RoHS does not restrict; the directive limits hexavalent chromium to 0.1 percent by weight per homogeneous material. Hard chrome and decorative nickel-chrome systems are compliant when properly controlled. What RoHS effectively bans is hexavalent chromate conversion coatings on zinc, replaced by trivalent chromium passivates. Ask your supplier to confirm trivalent passivation and provide a RoHS test report.

How long does gold plating last on jewelry?

It depends on thickness and wear. Decorative electroplated gold is typically 1 to 5 microns thick, and a micron-scale layer wears through on rings and bracelets faster than on pendants or earrings. For the EU market, the relevant requirement is nickel release under REACH. If longevity matters, specify a thicker deposit and confirm the underlayers in writing.

Can Chinese platers electroplate plastic parts?

Yes, ABS and some other plastics are routinely plated in China, mainly for automotive trim, sanitary fittings, and cosmetic packaging. The process needs chemical etching, a palladium catalyst, and an electroless copper or nickel underlayer before standard electroplating can proceed. Not every metal plater runs a plastics line, so confirm the capability and ask for plated-plastic samples specifically.

Rack plating or barrel plating: which should I specify?

Barrel plating suits small, durable parts like fasteners and is cheaper per piece, but thickness varies across the load. Rack plating mounts parts individually, giving uniform thickness and protecting visible surfaces from contact marks, at higher labor cost. For decorative finishes on visible parts, rack plating is the usual choice. Specify it on the purchase order rather than assuming.

Why did my plated parts start rusting a few months after delivery?

The most common cause is a nickel underlayer too thin or too porous to act as a barrier, sometimes combined with skipped pre-treatment. Salt-spray testing of incoming goods would usually have caught it. If you are seeing field failures, check retained samples against the original specification before reordering.

Your plating specification in one page

Before you place a plating order in China, write down these five items and get the supplier to confirm each in writing: the finish system by name; the minimum thickness in microns on significant surfaces; the corrosion test with standard, hours, and pass/fail criterion; the compliance requirements with the relevant test reports (RoHS, REACH nickel release for worn items); and the QC sampling plan for thickness and appearance. A supplier who answers all five precisely is usually worth keeping. One who waves them off is telling you something too.

If you need help finding a plater that meets those criteria, or verifying one you already found, email hi@cnally.com with your drawings and finish specification.