This is also known as penetrant Testing (PT), Liquid Penetrant Inspection (LPI) or Fluorescent Penetrant Inspection (FPI). It is a method used to find flaws is non-ferromagnetic materials, such as stainless steel, aluminum, etc. it is used on almost any non-porous materials. It is applied to the surface and left to soak, being drawn into any crack by capillary action. The excess penetrant is then removed using the cleaner and a developer is applied to draw out the entrant from cracks to enable a visual inspection of any defects.

The basic procedure that is followed to perform PT are as follows:

• Pre-cleaning of the specimen
• Application of penetrant
• Cleaning of the penetrant using cleaner reagent
• Application of developer
• Check for discontinuities/defects