V.S. Heat Treatment
Heat treatment & metal finishing experts
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V.S. Heat Treatment
Heat treatment & metal finishing experts
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A straight comparison between Cr3+ zinc electroplating (our in-house service) and zinc flake systems such as Dacromet/Geomet.
Zinc plating vs Dacromet / zinc flake
Cr3+ zinc electroplating gives bright colour options (white, blue, yellow) at low per-piece cost — the default for general screws, nuts and bolts. Dacromet (zinc flake) is applied without electricity, so it carries virtually no hydrogen-embrittlement risk and reaches several hundred salt-spray hours, but costs more and comes only in matte silver-grey or black. Grade 10.9+ bolts that are zinc plated must be hydrogen de-embrittlement baked — a service we run in-house.
| Decision factor | Cr3+ zinc electroplating | Dacromet / zinc flake |
|---|---|---|
| Principle | Electrolytic deposit + Cr3+ passivate | Dip-spin zinc-aluminium flake coating, oven-cured (non-electrolytic) |
| Typical thickness | About 5–12 µm | About 6–10 µm per coat |
| Colour options | White, blue, yellow iridescent — bright finish | Matte silver-grey or black |
| Typical salt spray | About 24–120 h (passivate/sealer dependent) | About 480–1,000 h (per coating-system spec) |
| Hydrogen embrittlement risk | Present for high-strength parts — managed by baking (ISO 4042) | Virtually none (no electrolytic or acid step) |
| Cost per piece | Lower — suits high volume | Higher; requires a specialist coater |
| Electrical conductivity | Conductive | Binder-based layer; less suited to electrical contacts |
| Typical use | General fasteners, decorative, indoor/moderate outdoor | Grade 10.9/12.9 bolts, automotive chassis and brake parts, high salt-spray specs |
Choose Cr3+ zinc plating for general fasteners that need corrosion protection plus an attractive colour at volume-friendly cost, with EU-export-ready Cr6-free passivation. For high-strength parts we run hydrogen de-embrittlement baking to standard.
Choose Dacromet/zinc flake when the customer or automotive spec demands several hundred salt-spray hours, or the part is grade 10.9+ where hydrogen embrittlement risk must be eliminated entirely.