Executive brief. Brass can be used in hypoallergenic jewelry systems when the finish stack, skin-contact components, and a testing/AQL plan are engineered together. This page translates EU/US nickel policies into practical actions and gives you acceptance criteria you can paste into a PO.
Who it’s for: OEM/ODM buyers, product managers, QC/compliance leads.
1) Brass 101: Properties, Pros & Where Allergies Start
- What brass is: Copper + zinc in various grades; highly formable, casting-friendly, and cost-efficient.
- Why it’s popular: Crisp cast detail, smooth polishing, broad plating color options — ideal for fashion price points.
- Where reactions happen: Not the base metal alone, but what touches the skin (plating composition, thickness, porosity) and which parts touch skin (ear posts/backs, clasps, extension chains).
Takeaway: “Hypoallergenic brass” ≠ bare brass. It’s a system: base metal + underplate + top layer + sealing + compliant contact parts.
2) Nickel Policies — EU vs US (Adult/Children)
| Market | Regulatory focus | Implications for brass jewelry |
|---|---|---|
| EU | Nickel release limits (more strict for piercing parts); migration tested in artificial sweat. | Engineer plating stacks to minimize release; substitute 316L/titanium for posts/backs; keep test reports per lot. |
| US (Adult) | Industry/retailer standards; marketplace policies vary. | Adopt nickel-safe finishes; keep supplier declarations; align wording with retailer acceptance. |
| US (Children ≤12) | Stricter limits on lead (often cadmium as retailer overlay); labeling and documentation. | Ring-fence children’s SKUs with separate specs, tests, labels; maintain lot-linked reports. |
3) Building a Hypoallergenic Brass System (Finish Architectures)
3.1 Nickel-safe plating stack (electroplating route)
- Underplate (diffusion barrier, nickel-safe): e.g., palladium or alternative nickel-free barrier.
- Precious top layer: specify thickness by wear class (≈ 0.1–0.3 μm fashion; 0.5–1.0+ μm premium).
- Transparent seal (optional): clear e-coat/organic lacquer to reduce porosity exposure and slow sweat ingress.
3.2 PVD + Brass hybrids (for wear hotspots)
- Keep the body in brass for design freedom and cost control.
- Use 316L/PVD for high-wear findings (clasps, chain ends, extenders) to stabilize skin contact and color.
3.3 Contact-part substitution
- Earrings: posts/backs in 316L or titanium; ornamental body in brass.
- Necklaces/bracelets: consider 316L/PVD for clasps and extension chains.
Color control: lock a golden sample; set ΔE00 ≤ 2.0 (premium ≤1.5) under D65/10° viewing. Record instrument model/geometry.
4) Test Plan You Can Enforce (Development → Incoming)
During development / pre-production
- Nickel release on skin-contact parts per target market.
- Heavy metals screening (children’s lines especially).
- Adhesion/abrasion sanity checks (rub cycles with graded visual assessment).
At incoming QC (per lot)
- Visual & dimensional checks (plating uniformity, porosity signs, burrs/sharp edges).
- AQL sampling plan (see Section 5).
- Periodic nickel-release spot checks on contact components (e.g., 1×/finish/quarter or per X lots).
- Retain test reports & supplier declarations with lot linkage.
5) AQL & Acceptance (Paste into Your PO)
Inspection level: ISO 2859-1 GII | AQL: Major 1.0 / Minor 2.5 (premium lines: 0.65 / 1.5)
| Defect class | Examples | Acceptance guidance |
|---|---|---|
| Critical (Reject) | Plating peel/blister; exposed base metal on skin-contact faces; sharp edges/burrs; failed ear-post attachment; wrong alloy for contact parts (not 316L/titanium when specified) | 0 tolerance; 100% rework or lot hold |
| Major | Visible pits/porosity clusters; color mismatch over ΔE00 limit; severe adhesion issues under light rub | Per AQL Major 1.0 |
| Minor | Fine swirls in non-prime areas; small label/pack errors without traceability loss | Per AQL Minor 2.5 |
6) Claims, Labeling & Documentation
- Prefer “nickel-safe” over absolute “nickel-free” unless you validate every lot.
- Keep CoC/CoA, nickel-release reports, and material declarations on file, linked to lots.
- Care card: avoid sunscreen/chemical exposure; rinse & dry after seawater; store separately.
7) Cost & Warranty Considerations
- Cost adds: nickel-safe underplate, thicker precious layer, contact-part substitution (316L/titanium), periodic testing.
- Cost saves: fewer returns/complaints, smoother marketplace onboarding, stronger retailer acceptance.
- Warranty idea: define a finish durability window by wear class (e.g., 6–12 months for daily-wear fashion plating) and an allergy-response protocol based on proof-of-purchase and lot ID.
8) Sourcing & Lead Times
- Barrier layers and thicker plating add lead time and may reduce line throughput; plan a pilot run (10–50 pcs) to validate adhesion/color.
- For peaks, standardize a library of brass bodies + 316L/PVD findings to reduce surprises.
9) FAQs
Can brass jewelry be truly hypoallergenic?
With the right plating stack and contact-part choices, you can achieve nickel-safe wear validated by release testing.
Do I need nickel tests on gold-plated brass?
Yes for skin-contact parts if policies require it; thickness alone doesn’t guarantee low release.
What if my marketplace has stricter cadmium rules?
Add cadmium checks to periodic screening and keep lot-linked reports for audits.