Liquid Penetrant Testing (PT)

Liquid Penetrant Testing (PT) is a non-destructive testing method used to detect surface-breaking defects in non-porous materials. In this process, a liquid dye—usually brightly colored or fluorescent—is applied to the surface of the material. The dye seeps into any cracks, porosity, or other surface imperfections through capillary action. After a specified dwell time, the excess dye is removed, and a developer is applied to draw out the penetrant from the flaws, making them visible under appropriate lighting conditions. PT is a cost-effective and straightforward technique commonly used in industries such as aerospace, automotive, and manufacturing to inspect welds, castings, and other components for surface defects.