Galvanized Before Welding or After Welding Which Should You Specify

Why the question matters

Welded wire mesh and welded mesh fence panels are both offered galvanized before welding and galvanized after welding. It sounds like a manufacturing detail. It is actually the single decision that determines where the product will start corroding.

Galvanized before welding

The wire is zinc coated, then welded. The parent wire is fully protected, but the heat of the weld burns the zinc back from each intersection, leaving a small bare nugget. In a dry building, indoors, or on a product with a short service life, that bare spot never becomes a problem and the lower price is worth having.

Galvanized after welding

The mesh is welded first, then galvanized as a finished panel or roll. The zinc covers the weld nuggets as well as the wire. It costs more and the coating is heavier, and in a washed-down poultry house, a coastal perimeter or any outdoor installation it is the specification that lasts.

What about PVC coating

PVC is applied over the zinc, not instead of it. It adds a polymer skin that resists salt and abrasion and is available in colour. Fence panels, chain link, hexagonal netting, welded mesh and insect screen are all offered PVC coated.

Where the cut edge fits in

Any cut, drilled or trimmed edge on galvanized-after-welding material exposes bare steel. Touch it up before backfilling a fence line. On galvanized-before-welding material the cut edge is no worse than the weld nuggets already are.

How to write it on the order

State the process, the sequence and the coating weight: for example hot dip galvanized after welding, 275 g/m2. On hot-dip galvanized iron wire the available coating range is 40 to 300 g per square metre. The word galvanized on its own does not specify anything a mill can be held to.