Galvanized before vs after welding: which is right for your filter?
Galvanized welded mesh is made in one of two ways, and the order of welding and galvanizing decides how well the weld points resist corrosion.
Galvanized before welding (GBW)
GBW starts with zinc-coated wire. When the wires are welded, the heat burns the zinc away at each joint and leaves bare steel at every weld. The rest of the mesh is protected, so GBW is a sound, economical choice for dry indoor service such as HVAC panel filters.
Hot-dip galvanized after welding (GAW)
GAW reverses the order. The mesh is welded first and the whole roll is then hot-dip galvanized, so zinc seals every joint. The coating is heavier and the welds are protected, which makes GAW the better choice where the filter will see humidity, condensation, outdoor air or industrial dust.
| GBW | GAW | |
|---|---|---|
| Weld joints | Bare steel | Zinc-sealed |
| Coating | Lighter, on the wire only | Heavier, over the whole mesh |
| Best for | Dry indoor HVAC | Humid, outdoor, industrial |
| Cost | Lower | Higher |
When to choose stainless
For wet or corrosive duty, stainless steel 304 or 316 welded mesh removes the coating question altogether. 316 is the usual choice where chlorides are present.
MAISHI makes both galvanized grades and stainless welded mesh. See the welded mesh page for sizes, or tell us where your filter runs and we will recommend a grade.
Related support media
Which grade does your filter need?
Tell us the filter type and where it operates.