The "Solid Brass" Door Handles Snapped at the Screw Boss

Brass vs Zinc Alloy Verification Guide

Hello, this is StartMade.

A brand selling solid wood furniture and interior accessories had a hardware factory in Gaoyao (高要), Zhaoqing, Guangdong, make door handles and drawer pulls. The design was a heavy piece in an antique gold finish, and the spec sheet said "Material: brass (全铜)." The approved sample felt substantial in the hand, and the first 3,000 pieces sold out without complaints. Sales were good, so five months later the brand reordered 8,000 pieces. At pre-shipment inspection, dimensions, color, plating appearance and screw fastening all passed.

About two months after the reorder went on sale, customer complaints piled up. Many said the door handle snapped right where the screw goes in, and photos showed bathroom handles where the plating had lifted to reveal gray metal underneath. When the remaining stock was cut open, the cross-section was silvery gray, not yellow. Only then did the brand confirm that the factory had switched the body to zinc alloy for the reorder and given it a brass-colored plating.

Once plated, brass and zinc alloy are almost impossible to tell apart by eye. Neither sticks to a magnet, and both come out of a mold in the same shape. But zinc alloy is lighter and softer than brass, cracks easily when force hits threads or thin sections, and corrodes white under the plating after long exposure to moisture. This post covers the differences between materials, the limits of each check, gaps in certificates, common supplier substitutions, and what to check in the spec sheet and at inspection.

One line saying "brass" or "全铜" and a sample are not enough. Set the alloy grade, copper and lead content ranges, material by component, unit weight and plating spec in the spec sheet, and check samples you pick yourself from production by weight and XRF, cutting them open when needed, to prevent breakage claims and recalls.

1. What "全铜" Can Hide

In the Chinese hardware market, "全铜" (all copper) usually means a brass body, but some factories use it for anything that looks copper-colored on the outside. Brass is an alloy of copper and zinc; the higher the copper, the heavier, tougher and more expensive it is. Zinc alloy (Zamak) is zinc with a little aluminum. Its low melting point lets factories die-cast complex shapes cheaply. Raw material for the same handle can differ several times in price, so it is the first thing to change when price pressure comes.

Zinc alloy is not a bad material in itself. For decorative parts that take little force or for indoor accessories, it works fine. The problem is paying for brass and getting zinc alloy, or having parts where force concentrates, such as threads, spindles and thin necks, switched to zinc. We also covered metal verification for stainless steel in Episode 150 and aluminum in Episode 157.

2. Checking Methods - From a Magnet to a Cross-Section

Ask "是全铜的吗?" and the factory almost always answers "当然全铜，你可以刮开看" (of course it's all brass, scratch it and see). Before you actually scratch anything, decide how you will check.

Weight Is the Cheapest, Fastest Filter

Brass has a density of about 8.4 and zinc alloy about 6.7, so the same shape in zinc alloy weighs about 20% less. Weigh the approved sample, write its unit weight in the spec sheet, and weigh a few dozen pieces on a digital scale at inspection; most lots with a switched material will show up. Weighing and scratching a hidden surface alone will catch a large share of problems on site.

Measure XRF Where the Plating Is Removed

Hold a handheld XRF directly on the plating and it picks up the nickel, chrome or brass-colored plating layer first. Strip a little plating from a spot hidden after installation, such as the base or inside a screw hole, to read the body material. XRF gives copper and zinc ratios right away and can tell H62 from H59, but if you need to confirm the grade or need evidence for a dispute, send samples for lab spark OES analysis. See Episode 10 for how to read test reports.

3. Approximate Criteria

Below are approximate values commonly referenced for quality control. Criteria differ by use and market and are revised often, so confirm the actual standard with a lab.

Unlike general hardware, faucets and water fittings also carry lead limits, so even brass may fail certification in the target market if it is leaded brass. Plating thickness measurement is covered in Episode 141, and salt spray testing in Episode 128.

4. Why You Can't Take Material Certificates and "全铜" at Face Value

Ask for proof of material and the factory usually sends the raw material supplier's mill certificate (材质证明) or a lab composition report. These documents have gaps.

5. Common Supplier Substitutions

Once plated, brass and zinc alloy look the same from the outside. When price pressure comes, factories start with materials and thickness you cannot see. Here are the patterns we have actually run into in consultations.

The most common pattern is switching the body to die-cast zinc alloy on a reorder. Forged brass and die-cast zinc use different molds, but most hardware factories either own both or can easily outsource to a die caster nearby. We covered requiring prior approval for material or process changes in Episode 119.

6. The Damage When the Material Changes

Material problems rarely show at pre-shipment inspection. They surface all at once as breakage and corrosion a few months after installation, and the damage spreads far beyond the product cost.

• Breakage and injury: When a zinc alloy handle snaps at the screw boss, someone can hurt a hand opening a door, and with shelf or cabinet pulls, items can fall.
• Leaks: If the body of a faucet or water fitting is zinc alloy or recycled brass, it can crack under water pressure and temperature changes, leading to leaks and even damage claims from the unit below.
• Certification problems: If leaded brass is found in parts that touch drinking water, certification can be revoked or sales halted.
• Brand trust: One review saying "they said brass, but it was zinc when I cut it open" casts doubt on the brand's other products too.

See Episode 53 for recalls and product liability, and Episode 36 for claims and disputes.

7. Items to Include in the Spec Sheet

Every factory reads a single "brass" line differently. Put the items below in a table and attach it to your spec sheet.

Writing unit weight into the spec sheet is tedious but has the biggest payoff. Whether the factory switches material or thins the walls, the weight changes. See Episode 59 for how to write spec sheets and BOMs.

8. Adding Material Checks to Your QC Checklist

Sample Stage

At the sample stage, set your reference values first. When you receive the approved sample, weigh each component and record composition with XRF after stripping plating from a hidden surface. Cut one piece open and photograph the section color and wall thickness, then seal the rest with the date and part number so you can compare later. We covered sample management in Episode 34.

Production Stage

Ask for the purchase invoice, mill certificate and package label photos on the day brass bar or ingot arrives at the factory. Check by photo whether incoming raw material matches the production quantity and whether zinc ingots or die-cast semi-finished parts are piled up in the workshop. See Episode 102 for production tracking.

Pre-Shipment Inspection Stage

The inspector picks packed products personally, weighs them, checks components with a magnet and measures hidden surfaces with XRF. If weight is noticeably lower than the approved sample or the zinc ratio jumps on XRF, cut a few open to check the section, then seal randomly picked samples and send them to a third-party lab. For handles and faucets, a screw torque test is worth adding. Pre-shipment inspection is covered in Episode 100, and screw fastening control in Episode 136.

9. Sample Request Wording for the Factory

Putting the wording below in your PO or spec sheet takes material out of the factory's discretion and makes it easier to assign responsibility if problems arise.

"本产品主体须使用H59及以上黄铜（GB/T 5231），不得使用杂铜、再生铜或锌合金。各零件材质须按材质清单执行，锌合金仅限我方书面确认的装饰件。涉水部件须使用无铅黄铜，铅含量不得超过0.25%。单件重量以确认样为准，偏差不得超过±3%，关键部位最小壁厚按图纸执行。如需更改材质、加工方式（锻造改压铸）或壁厚，须提前书面确认。每批原材料入厂时提供采购单据及材质证明，每批留存称重及XRF检测数据。出货前由我方随机抽取成品封样送第三方检测，如不合格，整批重做或退货，费用由供应商承担。"

10. Three Real Cases

These are anonymized patterns we often see in consultations. Amounts and figures are examples.

Case 1 - Antique Gold Door Handles

This is the case from the start of this post. Confronted with section photos, the factory insisted "the sample was the same material." With no sealed approved sample there was nothing to compare, but a record showing leftover stock from the first order weighed 22% more than the reorder became the decisive evidence. Because the spec sheet only said "brass" without unit weight or material by component, negotiations dragged on, and the brand absorbed about half of the replacement cost.

Case 2 - Kitchen Faucets

A company importing kitchen faucets measured the body with XRF at pre-shipment inspection and found lead several times higher than the approved sample. When asked, the factory said the price of the lead-free brass bar had risen, so it switched to leaded brass. The company stopped the shipment and had the lot remade, and now receives a composition report and bar purchase invoices for every lot.

Case 3 - Furniture Pulls and Roses

A seller importing cabinet pulls had confirmed the body was brass but never checked the rose under the pull or the screw boss. Complaints came in that on bathroom cabinets the plating near the rose was blistering and white powder was coming up. Only the rose turned out to be zinc alloy. Getting a component material list from the start would have prevented it.

11. Common Mistakes

The most common is believing it is brass because a magnet does not stick. Zinc alloy does not stick to a magnet either. Many buyers also pass a product because XRF on the plating showed copper, when the reading may simply be the plating layer. Checking only the body and letting components like spindles, screw bosses and roses slide, or assuming the reorder matches because the first order was fine, are frequent mistakes too. Accepting only the factory's raw material certificates without analyzing actual product, or setting no separate lead limit for faucets and water fittings, also turns into a big problem later.

12. Brass Hardware Material Control Checklist

Spec Stage

• Wrote the alloy grade and copper content range
• Wrote that recycled brass is not allowed
• Set a material list by component and which parts may be zinc alloy
• Wrote unit weight, tolerance and minimum thickness at key areas
• Wrote the lead limit for drinking water parts and the target market standard
• Wrote a prior approval procedure for material or process changes

Sample and Production Stage

• Set component weights and XRF reference values from the approved sample
• Cut one approved sample and recorded the cross-section
• Sealed and stored approved samples with date and part number
• Received purchase invoices and mill certificates for incoming raw material
• Checked workshop photos for die-cast semi-finished parts

Pre-Shipment Inspection Stage

• Weighed randomly picked finished products
• Checked components with a magnet and hidden surfaces with XRF
• Cut open suspect lots to check the section
• Sealed random samples and sent them to a lab for composition analysis

Wrap-Up - Check Weight and Cross-Sections, Not Plating Color

Handles leaving the factory shine the same gold whether they are brass or zinc alloy, and well-plated zinc alloy sometimes even looks finer. The difference shows up months after installation, at the screw boss and in the bathroom, and by then the whole shipment is in customers' hands. Writing the alloy grade, material by component and unit weight into the spec sheet, and checking weight and composition for every lot, costs far less than the replacements, damages and recalls you would pay for later.

There is also something you can do right now. Ask the factory currently in production for its component material list, recent raw material purchase invoices, composition reports and unit weight records. If the only answer is "都是全铜的，放心" (it's all brass, don't worry), build a brass hardware control sheet and send it before your next order.

StartMade supports you on the ground with spec sheets that set alloy grades and material by component, checks of mill certificates and purchase invoices, incoming raw material checks during production, and pre-shipment inspection including weight and XRF measurement and sealed samples. If breakage claims have already come in, we start by analyzing the remaining stock; if you are preparing new hardware, we start with the spec sheet together.