Why is it necessary to remove paint from a panel before MIG welding?

Removing paint from a panel before MIG welding is crucial primarily to ensure proper weld penetration. When paint is present on the surface of the metal, it can create a layer of insulation that prevents the heat generated during the welding process from effectively reaching the base materials. This can result in insufficient fusion between the weld metal and the base metal, leading to weak welds that could fail under stress.

The paint can also release harmful fumes when subjected to high temperatures, which can compromise the quality of the weld and present health hazards. By stripping the paint, the welder facilitates a clean surface that allows for optimal heat transfer and adhesion between the materials, ensuring a strong, durable weld. This preparatory step is essential for the integrity and safety of the welding process, particularly in applications where structural strength is critical.