When performing magnetic particle examinations, which type of particles gives the best sensitivity?

In magnetic particle examinations, fluorescent particles are considered to provide the best sensitivity. This is primarily due to their ability to fluoresce under ultraviolet (UV) light. When exposed to UV light, fluorescent particles emit a bright glow, which enhances visibility and allows for the detection of very fine surface and near-surface flaws in the material being examined.

This heightened visibility makes it easier for inspectors to identify defects that may not be as easily seen with other types of particles. The use of fluorescent particles typically leads to better contrast against the background, increasing the likelihood of detecting small cracks or discontinuities.

In contrast, while dry particles and colored particles can be useful in certain situations, they do not offer the same level of sensitivity under typical inspection conditions. Metallic particles, though effective for detection in some contexts, also lack the advantages provided by fluorescence.