Specification Guidance

Correct specification is vital – all zinc coatings are not the same!

Read our complete guideThe Importance of the Correct Specification of Metallic Coatings for Steel

Images of zinc coating

It is important to understand the difference between different zinc coatings – because they have different levels of corrosion performance and different suitability in their applications.

Only batch hot dip galvanizing, to EN ISO 1461, provides complete coverage of the steel component with a thick, strongly bonded layer of zinc by immersion of a fabricated steel article into molten zinc.

The process is also known as ‘general galvanizing’, ‘post galvanizing or ‘galvanizing after fabrication’ – but the most certain way to get the correct specification is to refer to EN ISO 1461.

Life in proportion to thickness

The life expectancy of a zinc or zinc alloy coating is largely determined by its thickness. Thicker coatings give longer life. Batch galvanizing to EN ISO 1461 gives fabricated steel products maximum protection through complete coverage with a thick, tough and metallurgically bonded coating.

Avoid confusion with continuously zinc and zinc-alloy coated steels

Steel sheet or strip can be coated with zinc (or zinc alloys) before fabrication. Steel sheet or strip is passed through a bath of molten zinc in a continuous process. When the steel is withdrawn from the molten zinc, the coating is mechanically wiped to produce a thin layer of zinc or zinc alloy. Sheet steels that are coated in this way are usually ordered according to EN 10346. Coatings with zinc are given the designation ‘Z’ ; zinc-aluminium alloys ‘ZA’ and zinc-aluminium-magnesium alloys are designated with ‘ZM’. Steel products that are manufactured from these ‘pre-coated’ steels will have thinner coatings and will have exposed steel at the cut edges and holes that are created during manufacturing – giving points of weakness in the future. It is important to recognise during specification that these types of continuously coated steels have lower durability and are less robust than a steel product that is galvanized after manufacture (to EN ISO 1461).

Other zinc coating types

Other types of zinc coating for steel include thermal sprayed zinc; electroplated zinc and zinc-rich paints. Each of these have their own specific applications and exhibit inferior characteristics to batch galvanizing in terms of coating thickness, adhesion and efficiency of application. It is important to recognise that these differences when specifying for corrosion protection. These other coating types are not equivalent to batch hot dip galvanizing to EN ISO 1461.

Benefits of specification to EN ISO 1461:

  • Optimal durability over multiple life cycles
  • Predictable performance based on ISO standards and decade of experience
  • Complete coverage – avoiding weakness at cut edges and holes
  • Reuseable and adaptable
  • Recyclable in existing recycling chain
  • Global specification fulfilled by local galvanizers

Keep up to date on EGGA's standardisation activities.
Learn more
Circular Economy
Galvanizing’s valuable role in the circular economy and reducing climate-related impacts of construction.
Learn more


The worldwide galvanizing industry’s premier conference and exhibition

European General 
Galvanizers Association

Follow us and keep up to date
Copyright © 2024 European General Galvanizers Association
Site by Fortico Media