When a penetrant is applied to a part by submerging the part in a penetrant bath, the part must

When a penetrant is applied to a part by submerging the part in a penetrant bath, the part must

• A. Remain in the bath for hours to ensure saturation
• B. Remain in the bath for days
• C. Remain in the penetrant bath only for long enough to ensure that the surface is covered with penetrant
• D. Be removed immediately after immersion

Answer: (C)

The key idea is how long to soak during the immersion step. When the part is immersed, you want the surface to be wetted with penetrant so that any surface-breaking defects can be filled by capillary action. Leave it in only long enough to ensure the surface is covered with penetrant, not for hours or days, and not to remove it immediately before it has a chance to wet the surface. If you stay in longer than necessary, you can get unnecessary penetration or background staining; if you remove it too soon, defects may not be penetrated. After this brief immersion, you remove excess penetrant and continue with the developer and inspection.

The key idea is how long to soak during the immersion step. When the part is immersed, you want the surface to be wetted with penetrant so that any surface-breaking defects can be filled by capillary action. Leave it in only long enough to ensure the surface is covered with penetrant, not for hours or days, and not to remove it immediately before it has a chance to wet the surface. If you stay in longer than necessary, you can get unnecessary penetration or background staining; if you remove it too soon, defects may not be penetrated. After this brief immersion, you remove excess penetrant and continue with the developer and inspection.