What is the effect of over removal of penetrant on test sensitivity?

• A. Increases sensitivity
• B. Reduces sensitivity
• C. No effect
• D. Causes excessive brightness

Answer: (B)

In liquid penetrant inspection, what matters is how much penetrant remains in surface-breaking flaws after the removal step. If you remove penetrant too aggressively, you scrub away penetrant that has already entered tiny cracks. With less penetrant left in the defects, there’s less material to be drawn out by the developer and revealed under UV or white light, so the indications become fainter or may disappear. That reduces the contrast between flaws and the surrounding surface, making small or tight defects harder to detect. So over removal lowers the test’s sensitivity.