Gold-plated dinner plates: US FDA food contact material testing requirements
Date：2025-11-28 09:49:41 Classification
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As metal products that come into direct contact with food, gold-plated plates do indeed require FDA compliance to balance the safety of the plating with the stability of the substrate. According to the US FDA 21 CFR and CPG guidelines, these products must pass three core tests—heavy metal leaching, plating adhesion, and substrate migration—before they can enter the US market.
I. Core Regulatory Basis and Testing Standards
Gold-plated plates must simultaneously meet two key FDA requirements:
1. Plating Material: Complies with FDA CPG 7117.05 "Metallic Plating in Food Contact Articles" (for gold, silver, and other precious metal plating).
2. Substrate Material: Complies with FDA 21 CFR 175.300 "Metals for Food Contact and Electroplating" (e.g., stainless steel, aluminum substrate).
Test Simulation Conditions:
- Acidic Food Scenario: Immersion in 4% acetic acid solution at 25°C for 24 hours.
- High-Temperature Use Scenario: Immersion at 95°C (e.g., when holding hot soup or hot dishes).
II. Mandatory Testing Items and Limit Requirements
1. Heavy Metal Leaching Test (Core Mandatory Test)
| Detected Substance | Test Method | FDA Limit | Key Impacts
| Lead (Pb) | 4% Acetic Acid Immersion Method | ≤0.5 μg/mL | Long-term intake may lead to neurotoxicity
| Cadmium (Cd) | 4% Acetic Acid Immersion Method | ≤0.25 μg/mL | Excessive intake may damage kidney function
| Nickel (Ni) | Acidic Simulation Solution Immersion | ≤0.1 μg/cm² | May cause skin irritation in individuals with nickel allergies
Example: Gold-plated stainless steel plates require simultaneous testing for heavy metal leaching from both the plating (gold) and the substrate (stainless steel) to ensure overall compliance.
2. Coating Physical Performance Testing
| Test Items | Test Methods | Acceptance Standards
| Coating Adhesion | Cross-cut Test + Tape Peel Test | No peeling, blistering, or cracking of the coating
| Coating Thickness Uniformity | X-ray Fluorescence Spectroscopy (XRF) | Gold plating thickness ≥ 0.5 micrometers (avoid localized exposure of the substrate)
| Coating Abrasion Resistance | Friction Test (500 cycles) | No exposure of the substrate; heavy metal leaching remains within acceptable limits after abrasion
Risk Point: If the coating thickness is insufficient or the adhesion is poor, it may peel off during use and enter the human body through food.
3. Substrate Migration Control
- Stainless Steel Substrate: Must comply with 21 CFR 175.300's limits on chromium and nickel migration (e.g., chromium ≤ 0.5 μg/mL)
- Aluminum Substrate: Additional testing of aluminum ion migration (≤ 0.2 mg/L when simulating acidic foods)
- Coated Substrate: If the underlayer is enamel or painted, it must also comply with 21 CFR 175.300's coating requirements (e.g., chloroform soluble extract ≤ 0.5 mg/in²)
III. Additional Requirements for Special Use Scenarios
1. Reusable Use Scenarios
- Requires 10 cycles of immersion testing (simulating daily washing-use cycles), and the heavy metal leaching level must still meet the standard after each test.
- Typical Scenarios: Washable gold-plated plates for restaurants, family tableware sets.
2. Single-use scenarios
- For single-use gold-plated paper or plastic plates (such as wedding party supplies), the following additional requirements must be met:
① FDA 21 CFR 176.170 (paper products) or 177.1520 (plastics)
② Bond strength between the plating and the substrate (to prevent delamination during use)
3. Distinguishing between decorative and functional plating
- Purely decorative gold plating (such as gold plating on the edge of a plate): Testing is still required on areas that come into contact with food (such as the inner surface of the plate).
- Full-surface gold plating: The entire plating must pass testing; testing only a portion of the plating is not acceptable.
IV. Practical recommendations for enterprise compliance
1. Process control:
- Use a "nickel undercoat + gold plating" process (nickel layer thickness ≥ 2μm) to enhance adhesion and reduce gold usage.
- Avoid using lead-containing solder or flux (as this can easily lead to excessive lead leaching).
2. Testing strategy:
- Initial Certification: Full testing (heavy metals + physical properties + substrate migration)
- Batch Control: Quarterly random checks for heavy metal leaching (focusing on lead and cadmium)
- Change Verification: Retesting is required when changing substrate or coating suppliers
3. Differences from EU CE:
- FDA focuses more on lead and cadmium leaching; the EU (EC 1935/2004) additionally requires nickel release ≤0.1 μg/cm²/week
- When exporting to both the US and European markets, it is recommended to use a gold plating thickness ≥1μm to meet both requirements.
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