Liquid Dye Penetrant Test - A liquid penetrant test is non-destructive type. It detects flaws that are open to the surface e.g., cracks, seams, laps, lack of bond, porosity, cold shuts, etc. It can be effectively used not only in the inspection of ferrous metals but is especially useful for non-ferrous metal products and on non-porous, non-metallic materials such as ceramics, plastics and glass.