A common frustration for procurement managers is receiving high-quality copper only to find it has turned black or green within weeks. While C10100 Oxygen-Free Electronic (OFE) copper is 99.99% pure, it is still highly reactive to atmospheric moisture, sulfur, and even fingerprints. Because C10100 is used in sensitive electronics and vacuum systems, preventing surface oxidation is critical for maintaining 101% IACS conductivity and ensuring reliable electrical contact.
Why does C10100 turn black or green so quickly?
Copper doesn't "rust" like steel, but it oxidizes. The first stage is a thin layer of cuprous oxide (Cu2O), which looks dull or brownish. If exposed to sulfur in the air, it turns black (Copper Sulfide). If exposed to moisture and CO2, it develops the classic green patina (Copper Carbonate).
Because C10100 Oxygen-Free Electronic copper is so pure, it lacks the protective alloying elements found in brass. Any surface contamination-especially the salts from a worker's hands-will accelerate this process, leaving permanent "handprint" stains that are difficult to remove.
Common Corrosion Types for C10100
| Corrosion Type | Appearance | Root Cause |
| General Oxidation | Dull / Brown | Exposure to oxygen and humidity |
| Sulfidation | Black | Airborne sulfur (common in industrial areas) |
| Pitting | Small green spots | Exposure to chlorides (salt air) or acids |
| Galvanic | White powder | Contact with Aluminum or Steel in moisture |
How can you protect C10100 from tarnishing during storage?
Preventing oxidation starts with the packaging. At GNEE METAL, we use VCI (Volatile Corrosion Inhibitor) paper and vacuum sealing for all C10100 Plate and Sheet and foils.
For long-term protection of C10100 Round, Square & Flat Bar, follow these rules:
Never touch with bare hands: Always use gloves.
Control Humidity: Keep the storage area below 50% RH.
Chemical Passivation: Use a mild citric acid or benzotriazole (BTA) dip to create a microscopic protective layer on the surface without affecting the 101% IACS conductivity.
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GNEE METAL Product Range
| Product Type | Shapes Available | Common Grades | Diameter/Thickness Range | Length/Width Range | Applications |
|---|---|---|---|---|---|
| Copper Tubes | Round, Square, Rectangular, Coiled | C10100, C10200, C11000, C12200, C12000 | OD: 0.5mm - 300mm Wall: 0.1mm - 20mm | Up to 6000mm or custom | HVAC, Plumbing, Heat Exchangers, Refrigeration, Hydraulic Lines |
| Copper Plates & Sheets | Flat Sheets, Perforated, Embossed, Tread Plate | C10100, C11000, C12200, C23000, C26000 | Thickness: 0.1mm - 200mm | Width: Up to 2500mm Length: Up to 6000mm | Electrical Busbars, Roofing, Cladding, Gaskets, Transformers |
| Copper Bars & Rods | Round Bar, Square Bar, Hexagonal Bar, Flat Bar | C10100, C11000, C14500, C17200, C18200 | Diameter: 1mm - 300mm | Length: 1000mm - 4000mm | Machined Components, Electrical Contacts, Busbars, Fasteners |
| Copper Wires | Round Wire, Flat Wire, Square Wire, Stranded, Braided | C11000, C11600, C17200, C17510 | Diameter: 0.05mm - 12mm | Coil weights: 1kg - 500kg | Electrical Wiring, Cables, Springs, Mesh, Welding Wire |
| Copper Strips & Coils | Thin Strip, Foil, Slit Coil, Profile Strip | C11000, C12200, C19400, C26000, C26800 | Thickness: 0.03mm - 5mm | Width: 2mm - 1000mm Coil ID: 300mm - 600mm | Transformers, Radiators, Shielding, Terminals, Connectors |
About Our Factory
We operate a full range of production lines including extrusion presses, cold drawing benches, high-speed rolling mills, slitting lines, and precision CNC machining centers, enabling us to produce copper tubes, plates, bars, wires, and strips entirely in-house. For quality assurance, we maintain a dedicated inspection laboratory equipped with spectral analyzers, universal testing machines, hardness testers, surface roughness testers, and optical measuring instruments. Every batch is tested for chemical composition, mechanical properties, and dimensional accuracy before shipment. Our production capacity reaches 500+ tons per month, and we hold ISO 9001:2015 certification with full traceability from raw material to finished product. Whether you need standard mill stock or custom-processed components, we deliver precision copper products with short lead times and complete material certification.
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