Fluorescent Particle Inspection methods (a.k.a., FPI and PT) are typically used to detect cracks, micro-shrinkage, or other discontinuities that are open or otherwise connected to the surface of a part being inspected. 

In general, FPI can be applied at any point during the manufacture and/or in-service use of an applicable part. Applicable parts are those made of ferromagnetic or non-ferromagnetic material, including some plastics and ceramics. FPI cannot be used on porous materials or parts with interfering coatings or contaminants. Surface defects as small as .015" (.38mm) can be reliably detected with FPI.

In aerospace applications for example, FPI is commonly used on aluminum and magnesium alloys, stainless steel, brass, and copper as well as graphite-epoxy composite materials. 
 

Disk under UV lighting.

We offer florescent penetrants for all levels of sensitivity, including Level 4 Ultrahigh. We also have various removers and developers. The most commonly requested FPI at our facility is the desired sensitivity penetrant, combined with a hydrophilic post-emulsified remover, and a dry powder developer. Please see our FPI literature for additional details of this technology.