Liquid Penetrant test is also called as Dye Penetrant Test or Penetrant Test. Liquid Penetrant Testing (PT) can be applied to detect surface discontinuities in all non-porous materials. This method can be applied for ferrous, non-ferrous, ceramics (tough and fired), Plastic etc.

PT can detect only surface discontinuities whose mouth is open to the surface.

LPI is used to detect casting, forging and welding surface defects such as hairline cracks, surface porosity, leaks in new products, and fatigue cracks in-service components.

White light is used for visible Liquid Penetrant Testing and Ultraviolet light (UV light) use for Fluorescent Liquid Penetrant Testing. The sensitivity is highest for Fluorescent Liquid Penetrant Testing.