In which situation is the wet fluorescent technique preferred over the dry technique?

The wet fluorescent technique is preferred in situations where increased speed and sensitivity are required. This technique utilizes a liquid suspension of magnetic particles that can flow into tight spaces and provide better coverage over large areas, making it highly effective for detecting fine surface cracks and defects.

The wet method allows for quicker inspection compared to the dry method because it can cover larger and more complex geometries more efficiently. Additionally, the fluorescent particles used in this technique tend to enhance visibility under UV light, allowing for both rapid detection of defects and the ability to see smaller discontinuities that may be missed with dry particles.

While the remaining options touch on certain conditions, they do not highlight the primary advantages of wet fluorescent testing, which focus on its effectiveness and efficiency in revealing surface flaws in a timely manner. In essence, the combination of liquid suspension, the high sensitivity of fluorescent particles, and quick application makes this technique ideal for inspections that require immediate results and detailed evaluation.