Which statement is NOT a stated requirement for penetrant to perform well?

• A. Capable of flowing smoothly and evenly over the test piece
• B. Capable of entering and filling surface openings
• C. Can remain in surface opening during removal of excess penetrant
• D. Non-conductive to the part

Answer: (D)

The thing being tested is what properties a penetrant must have to reveal surface defects effectively. For liquid penetrant inspection to work, the liquid must wet and flow smoothly over the surface so it can reach tiny openings; it must be able to enter and fill those surface openings to enter defects by capillary action; and it must stay in those openings long enough so that, after excess penetrant is removed, it remains in the defect to be revealed when the developer is applied.

Being non-conductive to the part is not a required property for penetrants to perform well. Electrical conductivity isn’t part of how penetrants reveal defects in surface-breaking flaws, so this characteristic isn’t a stated necessity for effective LPI.