What are common brass alloy compositions used?

For a skin-contact bracelet, manufacturers commonly evaluate copper-zinc grades such as nominal 70/30 brass, often identified as UNS C26000, and nominal 65/35 brass, commonly identified as UNS C26800. These are wrought alpha-brass families with useful formability. The copper-to-zinc ratio is only one part of suitability: residual lead, nickel in the plating system, surface porosity, and corrosion behavior also require review. Lead-free does not automatically mean hypoallergenic, because individual reactions can involve copper, zinc, nickel, or finish chemicals. Request the declared composition and restricted-substance evidence for the exact production lot rather than approving a generic term such as jewelry brass.

The 65/35 designation generally describes brass containing about 65% copper and 35% zinc by nominal composition. Increasing zinc from a 70/30 grade typically changes color toward a more yellow tone and can alter forming behavior, hardness, and polishing response. Actual limits depend on the governing material specification and mill tolerances. For a linked bracelet, the relevant question is not simply which ratio looks best; it is whether the grade can be stamped, formed, soldered, or machined without cracking at the selected thickness. Approve the alloy using a production-representative sample, especially where links, prongs, hinges, or thin edges create localized stress.

A lead-free or controlled-lead alloy is often the safer starting point for export jewelry, but the applicable requirement depends on destination, age classification, component accessibility, and sales channel. Some brass grades used for easy machining contain intentional lead, such as free-machining C36000, and should not be treated as an automatic choice for skin-contact components. EU REACH restrictions, U.S. federal requirements, California Proposition 65, and retailer standards can address different substances and thresholds. A buyer should define the destination markets before material approval, then request composition declarations and relevant test reports for the finished article, including the base metal and plating layers.

Plating performance depends on the complete surface system, not only the copper-zinc ratio. Brass must be correctly cleaned, activated, and prepared before any barrier or decorative layer is applied. Zinc-rich surfaces can behave differently during chemical preparation, while polishing residue, porosity, sharp edges, and inconsistent geometry may cause skips, blistering, or accelerated wear. Sweat, friction against clothing, clasp movement, and exposure to cosmetics are practical wear factors for a tennis-style design. Buyers should specify the target color, underlayer or barrier requirements, decorative metal, thickness range, adhesion method, and finish test criteria. A production sample tested after handling gives more useful evidence than a color panel alone.

Recycled brass can be suitable when its composition and supply chain are controlled, but the word recycled does not establish regulatory compliance. Scrap streams may introduce lead, cadmium, nickel, iron, or other contaminants that change the final chemistry. The supplier should identify the permitted recycled content, maintain lot traceability, and provide composition information for the material used in production. Finished jewelry may still require substance testing because plating, solder, stones, and findings can contribute separate compliance risks. For a private-label order, include recycled-content expectations, restricted-substance limits, documentation format, and retesting triggers in the purchase specification rather than relying on a broad sustainability statement.

Before approval, request the proposed grade or controlled composition range, a material declaration, evidence of lead and other restricted-substance controls, and a sample made with the intended forming and finishing process. Also confirm the plating stack, decorative-metal thickness target, solder or adhesive use, stone-setting method, and inspection standard. The sample should represent production geometry because a flat test coupon cannot reveal link distortion, clasp stress, edge wear, or plating coverage around settings. For multi-market distribution, provide the destination countries and retailer requirements at quotation stage. The final purchase specification should identify the approved alloy, finish, test scope, acceptance criteria, and procedure for handling any material substitution.