When using radiographic inspection, defects such as cracks and porosity show up as:

In radiographic inspection, the process involves passing radiation through the material being examined and capturing the resultant image on photographic paper or film. The key principle at play is that different densities of materials absorb radiation to varying degrees.

When defects such as cracks and porosity are present, these areas are less dense than the surrounding material. As a result, they allow more radiation to penetrate through them, leading to greater exposure of the photographic paper. This increased exposure causes those areas to appear darker on the developed film. Consequently, cracks and porosity manifest themselves as darker shadows on the photographic paper, making it easier to identify these flaws during the inspection process. This contrast between the solid material and the defects is critical for the effective evaluation of the integrity of the component being inspected.