// FINISHING — ZINC PLATING
Zinc Plating Rack & Barrel
Zinc electroplating on steel parts and threaded fasteners — rack and barrel capacity, multiple chromate finishes, ASTM B633.
Zinc electroplating deposits a layer of zinc onto steel to provide sacrificial corrosion protection: the zinc corrodes preferentially, shielding the base steel from rust. It is one of the most widely specified surface treatments for steel hardware, fasteners, brackets, and structural components where cost-effective corrosion resistance is required. Rigid Concepts coordinates zinc plating through our trusted finishing partner NorTex Metal Finishing, with both rack and barrel capacity.
Rack vs. barrel plating
Rack plating is used for parts that must be individually fixtured — typically larger components, precision parts, or anything where surface contact marks cannot be tolerated. Barrel plating is the efficient process for high volumes of small parts: fasteners, bolts, washers, pins, and similar hardware tumbled in a rotating barrel for uniform coverage. NorTex offers both, and the right method is determined by your part geometry, volume, and finish requirements.
- Rack plating for larger, precision, or geometry-sensitive parts
- Barrel plating for high-volume small parts and fasteners
- Clear, black, yellow, and olive drab chromate passivates available
- Threaded parts and steel hardware — a core application
Chromate passivate colors
After zinc plating, a chromate conversion passivate is applied to further slow corrosion and seal the zinc. The passivate choice determines appearance and baseline salt-spray performance:
- Clear (trivalent): bright, silver appearance — most common RoHS-compliant finish
- Yellow: gold-yellow iridescent — classic hex/trivalent chromate appearance, higher baseline corrosion hours
- Black: matte black — low-reflectivity applications and aesthetics
- Olive drab: military-style dull green-brown — specified for some defense hardware
Material and size capability
Zinc plating is applied to steel and iron substrates. NorTex handles rack parts up to 32" × 30". Barrel capacity is suited to the small-part volumes typical of fastener lots.
| Process | Zinc electroplating (rack & barrel) |
|---|---|
| Passivate colors | Clear · Yellow · Black · Olive drab |
| Max rack size | 32" × 30" |
| Substrate | Steel, iron |
| Primary application | Fasteners, bolts, brackets, structural hardware |
| Standard | ASTM B633 |
For steel parts that need a purely aesthetic surface treatment with minimal buildup and no dimensional impact, see black oxide coating. For stainless steel parts, passivation is the appropriate corrosion treatment.
// FAQ
Frequently asked questions
Use rack plating for larger parts, close-tolerance features, or parts where contact marks cannot be tolerated. Use barrel plating for high volumes of small hardware — fasteners, pins, and similar — where individual racking would be cost-prohibitive.
The zinc deposit is the same; the difference is the chromate passivate applied afterward. Clear (trivalent chromate) gives a bright silver look and is the standard RoHS-compliant finish. Yellow gives a gold iridescent appearance with slightly higher corrosion protection. Black chromate provides a dark matte look. Olive drab is specified for certain military and defense applications.
Yes, but the buildup is thin — typically 0.0002" to 0.0005" per side for standard decorative zinc. Heavier deposits are possible but less common. For threaded parts, plating thickness must be considered against thread class — this is standard practice for fastener plating.
ASTM B633, the standard specification for electrodeposited coatings of zinc on iron and steel.
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