What is ZAM Coating? Zinc-Aluminium-Magnesium Explained
ENSOL Engineering TeamPublished 2026-02-011 min read
ZAM is a metallic coating of zinc alloyed with aluminium and magnesium. The magnesium gives it a distinctive property: it 'self-heals' at cut edges and scratches, so ZAM protects better than plain zinc even where the steel is exposed by drilling or shearing.
Composition and behaviour
ZAM combines zinc with a few percent each of aluminium and magnesium. The alloy forms stable, dense corrosion products that slow further attack, delivering strong protection at a lower coating mass than plain galvanising.
Self-healing at cut edges
When steel is cut or drilled, the exposed edge normally corrodes first. With ZAM, magnesium-rich products migrate over the bare edge and re-passivate it — the reason ZAM performs well on sheared and punched members.
When to choose ZAM
ZAM suits coastal and aggressive environments, and projects that want long life without the mass of hot-dip galvanising. ENSOL offers ZAM alongside GP, GL and HDGI so the coating can be matched to the site.