The Liquid Penetrant (PT) method of inspection is based on the penetration of a liquid with certain characteristics of capillarity, viscosity, wettability and density within a discontinuity outcropping on the surface. Non-destructive testing using the liquid penetrant method is a surface integrity inspection procedure with respect to outcropping defects on metallic materials. Typically, the penetrant is red in color (a color related to the presence of anelin), while the detector (based on amorphous silica) is white in color. This color difference allows any surfacing defect to be easily visible.