Non-Destructive Testing (NDT) Practice Test

Which of the following is NOT a characteristic of fluorescent penetrants?

1. They are water-based.

2. They provide high visibility under UV light.

3. They can detect very small cracks.

4. They are typically used for non-porous materials.

The correct answer is: They are water-based.

Fluorescent penetrants are designed to be highly effective in detecting surface flaws, and their primary characteristic includes the ability to fluoresce under ultraviolet (UV) light, providing high visibility that enhances the detection of defects. When considering the characteristics of fluorescent penetrants, it's important to note that they are primarily oil-based rather than water-based. This oil-based formulation allows for better penetration into the surface cracks and provides the necessary properties for effective inspection. The other options highlight true attributes of fluorescent penetrants. Their ability to detect very small cracks makes them particularly useful in applications where precision is critical. They also adhere well to non-porous materials, ensuring that the penetrant does not seep away from the detection area, which could lead to missed defects. Therefore, stating that fluorescent penetrants are water-based does not align with their actual formulation, making that option the one that is not a characteristic of fluorescent penetrants.