What is a significant disadvantage of Dye penetrant inspection (DP)?

Dye penetrant inspection (DP) is a widely used non-destructive testing method that identifies surface defects in non-porous materials. A significant disadvantage of this technique is that it is not applicable to porous materials. The method relies on the ability of a liquid penetrant to seep into defects and reveal them when viewed under UV light or under a visible light source. In porous materials, the penetrant can seep into the material's structure rather than locating specific surface flaws, rendering the technique ineffective. Therefore, the inability to apply DP to porous materials is a critical limitation of this inspection method, emphasizing the importance of selecting appropriate testing methods based on material characteristics and flaw types.