In VT, why is direct lighting aimed at weld toes?

• A. To reveal cracks at toe locations
• B. To heat the weld
• C. To cool the surface
• D. To confuse the inspector

Answer: (A)

Direct lighting in visual testing is used to make surface flaws stand out by creating shadows and strong contrast at the surface features. A shallow, oblique light aimed at the weld toes highlights cracks that typically run along or near the toe by causing subtle interruptions in the surface and changing how the light reflects off the metal. Weld toes are common crack initiation points due to stress concentration and the geometry where the heat-affected zone meets the base metal, so revealing defects there is especially important. This lighting approach isn’t about heating or cooling the weld, and it isn’t meant to mislead the inspector; it’s all about making cracks visible.