Dye/Liquid Penetrant Examination (PT)

Dye Penetrant Examination involves applying a liquid to the surface of a material and leaving it to rest for a pre-determined period of time. The liquid, the so called penetrant can be either a colour that is easily visible under normal lighting conditions or a yellow/green fluorescent colour that requires special lighting conditions to be effective.

The penetrant once applied to the surface penetrates the defects. After some time the penetrant fluid is washed off the surface. With a developer applied to the now clean surface, the defects where the fluid has penetrated are made visible. These spots are called indications. Acceptance criteria define whether or not the indication is non-acceptable (a defect) or not.