Which indication during PT signifies a defect in the material?

The presence of color changes or spots after applying the developer signifies a defect in the material during Liquid Penetrant Testing. When penetrant is applied to a surface, it seeps into any discontinuities such as cracks, porosity, or other defects. After removing the excess penetrant and applying the developer, it acts as a contrasting background that brings out the penetrant trapped in these discontinuities. If defects are present, the developer will show distinct color changes or spots in the areas where the penetrant has accumulated, indicating that there is an imperfection within the material.

In contrast, a uniform surface finish, no markings on the surface, or increased surface luster do not indicate any defects. A uniform finish suggests that the surface is free from significant discontinuities, while no markings imply a lack of penetrant retention, indicating sound material. Increased surface luster may result from polishing or surface treatments, but it does not pertain to defect indications in the context of penetrant testing. Understanding these distinctions is crucial for accurate interpretation of results in Liquid Penetrant Testing.