Causes of Porosity

Possible Solutions


Impurities on base metal

  1. Remove contamination; clean surfaces
  2. Use of specific wire/gas mix for specific types of impurities


Impurities on filler metal (wire)

  1. Replace wire
  2. Install wire-cleaning system
  3. Prevent industrial dust/dirt/grit from contaminating wire during storage or use
  4. Prevent build-up of aluminum oxide on exposed aluminum wire surface by using up quickly
  5. Remove wire from wire drive unit and store in a sealed plastic bag when not in use for long periods


Drafts, wind, fans, etc.

  1. Protect weld from drafts (curtains/screens)
  2. Use tapered or bottleneck gas nozzles when drafts cannot be avoided


  1. Too high a gas flow, causing turbulence, and/or sucking air at hose connections; creating the venturi effect at end of gas nozzle
  2. Too low a gas flow, causing insufficient gas coverage
  3. Damaged or kinked gas lines
  4. Too high an oxygen content
  5. Leaks in gas distribution system
  6. Other impurities in gas - moisture, etc.
  7. Inconsistent gas flow (cfh) at the torch connection
  1. a. Reduce gas flow
    b. Tighten all hose connection points
  2. Increase gas flow
  3. Repair or replace
  4. Adjust mixer
  5. Repair leaks
  6. Overhaul system; fit filters and/or dryers
  7. Regulate pressure into flow meter for consistent cfh delivery of gas


  1. Excessive spatter build-up in gas nozzle and on current tip
  2. Nozzle damage, causing uneven gas coverage
  3. Torch gas ports clogged or deformed
  4. Super-heated nozzle, causing shielding gas to expand rapidly and create return effect at end of nozzle
  5. Gas diffuser/nozzle insulator missing
  6. Too high a gas flow causing the venturi effect
  1. Clean nozzle and tip regularly; spray with anti-spatter fluid
  2. Replace nozzle
  3. Clean or replace
  4. Check duty cycle rating of torch
  5. Replace
  6. Reduce gas flow


  1. Too long a wire stick-out; gas nozzle too far from weld puddle
  2. Bad torch position - too sharp a torch incline causing the venturi effect at the end of the nozzle leading to atmospheric contamination
  3. Excessively wide weld pool for nozzle I.D.
  4. Arc voltage too high
  5. Too high a travel speed
  1. Use longer nozzle or adjust stick-out (3/8" minimum or 15 times wire diameter)
  2. Correct torch angle
  3. Width of the weld pool should be 1.3 times the nozzle I.D.; use suitable wider gas nozzle
  4. Reduce voltage
  5. Reduce speed