Full definition
NDT technique that detects surface discontinuities (cracks, porosity, laps) in non-porous materials. 5-step process: pre-cleaning, penetrant application (red visible or UV fluorescent) for 5-30 min, excess removal, white developer application (absorbent), visual inspection. Cracks appear as colored or fluorescent lines. Standards: ASTM E165, ISO 3452. Applicable to metals, plastics and ceramics. Does not work on porous materials or compression-closed cracks.