What is hot-dip galvanizing and how does it work?
Hot-dip galvanizing is a metallurgical process that protects steel and iron from corrosion by coating them with a layer of zinc. This coating is applied by immersing the metal in molten zinc at approximately 450°C. The result is a tough, long-lasting barrier that provides both physical protection and cathodic shielding, ensuring superior resistance even in aggressive environments.
The process is regulated by international quality standards, such as ISO 1461, which define coating thickness, uniformity, and inspection criteria.
Main steps of the hot-dip galvanizing process
1. Degreasing
The metal surface is cleaned to remove oils, greases, and residues from manufacturing.
2. Pickling
Acid treatment is used to eliminate rust, scale, and oxides, exposing the raw surface.
3. Fluxing
The component is dipped in a zinc ammonium chloride solution to prevent oxidation and improve zinc adhesion.
4. Drying
Residual moisture is removed to ensure a safe and effective zinc immersion.
5. Immersion in molten zinc
The cleaned and prepared part is submerged in molten zinc, forming a zinc-iron alloy bond that protects the base metal.
6. Cooling and inspection
After galvanizing, the piece is cooled in air or water, then checked for surface quality, coating thickness, and structural conformity.
Reference standards and regulatory compliance
In the European Union and globally, ISO 1461 is the primary standard governing hot-dip galvanizing. It covers:
- Minimum zinc coating thickness based on material type and dimensions
- Visual acceptance criteria (no significant lumps drips or bare areas)
- Methods for measuring coating thickness and ensuring consistency
- Handling and documentation requirements
Compliance with ISO 1461 ensures not only corrosion protection, but also technical traceability and repeatable quality.
Zincol Lombarda: certified quality and process control
Zincol Lombarda applies the full hot-dip galvanizing process in-house, ensuring strict control over each stage—from surface preparation to final inspection. Operating throughout Milan, Lecco, Bergamo, and Como, the company offers high-volume capacity and custom solutions tailored to structural steel, carpentry, and industrial components. With a commitment to Made in Italy quality, Zincol Lombarda guarantees coatings that meet or exceed ISO 1461, backed by experienced technicians and traceable process data.
