Why is coating thickness important?
The zinc coating thickness achieved during hot-dip galvanizing is a key factor in determining the long-term corrosion resistance of the treated steel or iron. Thicker coatings offer extended durability, especially in outdoor or industrial environments where exposure to moisture, chemicals, or air pollutants is constant.
To ensure quality and performance, coating thickness is regulated by the UNI EN ISO 1461 standard, which defines minimum requirements for protective zinc layers based on the type and thickness of the base material.
Standard requirements according to UNI EN ISO 1461
The ISO 1461 standard specifies minimum average zinc coating thickness values based on the nominal thickness of the steel:
| Base Material Thickness | Minimum Average Zinc Coating (μm) |
|---|---|
| ≥ 6 mm | 85 μm |
| 3 – 5.9 mm | 70 μm |
| < 3 mm | 55 μm |
These values are determined by taking multiple measurements on representative surfaces using calibrated instruments (such as magnetic or eddy current gauges).
The standard also sets:
- Acceptance criteria for surface finish
- Guidelines for handling and marking
- Procedures for re-galvanizing if minimum thickness is not achieved
Factors affecting zinc thickness
While ISO 1461 defines minimum requirements, actual zinc coating thickness can vary depending on:
- Steel chemistry (silicon and phosphorus content in particular)
- Immersion time in molten zinc
- Surface condition and cleanliness of the component
- Cooling and withdrawal speed
In some cases, coatings may exceed standard values for extra protection in aggressive environments, such as coastal or industrial zones.
Zincol Lombarda: guaranteed compliance and full traceability
Zincol Lombarda applies strict process control to ensure each galvanized component meets or exceeds the coating thickness requirements of UNI EN ISO 1461. Every batch is inspected and measured using certified equipment, and results are traceable for quality assurance.
Serving clients across Milan, Lecco, Bergamo, and Como, Zincol Lombarda delivers Made in Italy precision and reliability, with personalized support for construction firms, manufacturers, and technical designers.