Troubleshooting

Why is my mig welding porosity?

Quick answer

Porosity in mig welding usually means gas shield interrupted — wind, empty bottle, loose fittings, or dirty/oily steel. For this process, check gas flow and wind first before touching anything else.

· · Technical guidance compiled from trade practice and manufacturer data; our source-verification program is in progress — see our editorial policy.

The specific fix

Check gas flow and wind first. The general rule: check gas first: flow, leaks, leaks at the regulator; shelter the arc; clean the joint.

Process checklist

  • Stick-out too long — keep 8–10 mm from nozzle to work for a stable arc
  • Travel too slow on thin sheet, burning holes instead of building a bead
  • Wrong wire size for the job — 0.9 mm covers most hobby work in Australia