What happens
Galvanizing is a zinc coating, and zinc boils at around 900 °C (1652 °F) — well below the temperature of a weld pool. The vapor oxidizes into fine zinc oxide fume, which causes « metal fume fever »: flu-like symptoms hours after exposure, typically passing within a day or two. It is unpleasant, and repeated exposure is not something to accumulate.
Grind it back
Remove the coating from the weld line and 20 to 25 mm (0.79 to 0.98 in) either side with a flap disc or a wire wheel before welding. That removes most of the fume at source and improves the weld — zinc contamination causes porosity as well as illness.
Extract and ventilate
Both. Capture at the arc with an extractor nozzle close in, and work with air moving across the bench and away from your face. Outdoors, stand upwind. This is the material where the two together matter most.
Afterwards
Bare steel at the weld will rust. Cold galvanizing paint or zinc-rich primer restores protection at the joint, which is the standard repair for galvanized structures.
The questions welders ask
Is drinking milk a real remedy?
No. It is a workshop myth with no basis — nothing you drink prevents inhaled zinc oxide from causing metal fume fever. The only effective measures are removing the coating, extracting the fume and ventilating the space.
Can I weld galvanized without grinding it back?
It is done constantly, and it produces more fume and more porosity. If the joint is structural or will be inspected, grind it. If it is a field repair on a fence post, extract, ventilate, stand upwind and accept a poorer weld.
Last reviewed 2026-08-14