penetrant inspection

The dye-penetrant method is one of the oldest non-destructive testing methods for determining surface defects. The test can be performed on almost all metallic and non-metallic materials. In this process, the capillary action of the test liquid causes it to penetrate into surface defects of any kind of material. After careful washing of the solution, a developer layer is applied which creates a counter capillarity. This draws out the liquid that has penetrated into cavities and cracks and makes the defect visible.