When exporting galvanized steel sheets, zinc coating thickness plays a vital role in determining corrosion resistance, salt spray test performance, and overall cost-effectiveness. The two common coating options—85μm and 55μm—each serve different needs depending on application environment and market standards.
✅ Salt Spray Test Duration: 85μm vs 55μm
Salt spray testing, following standards such as ASTM B117 or ISO 9227, is widely used to assess corrosion resistance:
85μm zinc coating can withstand salt spray exposure up to 600–720 hours before red rust appears.
55μm zinc coating typically endures 240–360 hours, suitable for mild environments or short-term applications.
The thicker 85μm layer offers significantly longer protection, especially in coastal, industrial, or marine environments where corrosion is a major concern.
✅ Export Cost-Performance Comparison
From a cost-performance perspective:
55μm galvanized sheet is more budget-friendly and sufficient for indoor or dry climate use.
85μm galvanized sheet, though higher in initial cost, delivers long-term value through reduced maintenance, longer life cycle, and higher export quality acceptance, especially in markets with strict durability requirements.
Many countries in Europe, Middle East, and Southeast Asia prioritize corrosion resistance in import specifications, favoring thicker zinc coatings.
✅ Application Scenarios
Zinc Coating Recommended Use Case
55μm Indoor structures, HVAC ducts, furniture, low-humidity environments
85μm Outdoor enclosures, marine zones, industrial buildings, export to high-humidity or coastal markets
✅ Conclusion
Choosing between 85μm and 55μm zinc coatings depends on target market, end-use environment, and long-term performance goals. For exporters, offering both options with clear salt spray test data and compliance certifications enhances competitiveness and customer trust.