On a radiograph, does a slag inclusion appear as a light or dark area?

A slag inclusion appears as a dark area on a radiograph. This occurs because slag inclusions are generally less dense compared to the surrounding base material or weld metal. In radiographic testing, areas that are less dense allow more radiation to pass through, resulting in darkening on the film or detector. Since slag inclusions are typically non-metallic and have different physical properties than the metals they are surrounded by, they do not show up as well-defined or lighter areas. Instead, they create contrast in the image by appearing darker than the surrounding weld or base metal. This understanding allows weld inspectors to identify potential defects in welds and assess the quality of the welding process effectively.