Why does my weld have tungsten contamination?

Root causes

Dipping the electrode in the pool or touching filler to the tip.

The fix sequence

• regrind the tungsten; hold 2–3 mm stand-off and feed the rod into the leading edge of the pool
• Change one variable at a time and re-test on scrap
• Re-inspect the finished bead — chisel, brush, look

When to grind it out

Structural or pressure work with visible defects: grind back to sound metal and re-weld — never 'cap over' a defect and hope. For non-critical jobs, judge honestly: a cosmetic defect is a learning note; a fusion or crack defect is a redo.