Welding Slag

Welding flux is used to protect the weld area from contamination.  The flux forms a protective layer over the surface.  In certain cases, it is left as a residue over the weld area.  This is called welding slag.

Welding Slag has to be removed in order to be able to view the welded area for inspection as well for aesthetics and visual appearance.  Welding slag can be chipped away with a pointed hammer.  Sometimes, it is also removed by grinding.