Which of the following is NOT a typical cause of porosity in welds?

• A. Moisture in electrodes or filler
• B. Contamination on base metal
• C. Proper shielding gas coverage
• D. Improper technique

Answer: (C)

Porosity happens when gas gets trapped in the molten weld metal as it solidifies. Moisture in electrodes or filler introduces hydrogen gas into the weld pool, which can form pores as the metal cools. Contamination on the base metal—like oil, grease, dirt, or rust—releases gases or interferes with proper shielding, creating pathways for gas pockets to form. Improper technique, such as incorrect travel speed, arc length, or poor joint preparation, can disturb the molten pool and shield, allowing air or gases to become trapped. Proper shielding gas coverage, when done correctly, actually protects the weld from atmospheric contamination and helps prevent porosity, so it is not a typical cause. Only if shielding gas coverage is inadequate would porosity occur, making this option the one that is not a typical cause.