Which surface contaminants are particularly problematic for MIG welding on painted panels, and how are they removed?

• A. Oil, wax, silicone-based lubricants, and rust; remove with solvent degreaser, mechanical abrading, and wipe-down with clean solvent.
• B. Only dust and moisture; wipe with water.
• C. Paint only; sand with 80 grit.
• D. Metal burrs; grind until shiny.

Answer: (A)