Oil on the surface should be removed prior to penetrant testing.

Oil on the surface should be removed prior to penetrant testing.

• A. False
• B. Sometimes
• C. Not necessary
• D. True

Answer: (D)

Surface cleanliness is essential in penetrant testing; oil on the surface must be removed. The penetrant method relies on capillary action to flow into surface-breaking defects and then be drawn out by the developer to create visible indications. If a film of oil coats the surface, it acts as a barrier that prevents the penetrant from wetting and entering cracks, and it can trap penetrant in a thin layer instead of letting it reach defects. This can mask real flaws or produce misleading indications, degrading the reliability of the test. Cleaning away oil (with appropriate solvents or detergents) ensures proper wetting, accurate penetration, and clean developer flow, leading to valid, detectable indications.

Surface cleanliness is essential in penetrant testing; oil on the surface must be removed. The penetrant method relies on capillary action to flow into surface-breaking defects and then be drawn out by the developer to create visible indications. If a film of oil coats the surface, it acts as a barrier that prevents the penetrant from wetting and entering cracks, and it can trap penetrant in a thin layer instead of letting it reach defects. This can mask real flaws or produce misleading indications, degrading the reliability of the test. Cleaning away oil (with appropriate solvents or detergents) ensures proper wetting, accurate penetration, and clean developer flow, leading to valid, detectable indications.