Liquid Penetrant Inspection (LPI) – Effective and low cost non-destructive testing procedure designed to detect and expose surface connected defects in non-porous materials (non-ferrous metal, plastic or ceramic components). The method relies on the physical interaction between an appropriately formulated chemical liquid and the surface of a part. This interaction causes the liquid to enter the surface cavities and later to emerge, visually indicating the location and the approximate size of the surface defect. Relatively easy to use, LPI has a wide range of applications. Because it uses physical and chemical properties rather than electrical or thermal phenomena, it can be used in the field, far from power sources. LPI is also used for leak testing.