Which inspection technique is used to reveal defects by applying a colored dye and checking for bleed-out on the surface?

Which inspection technique is used to reveal defects by applying a colored dye and checking for bleed-out on the surface?

• A. Magnetic particle inspection
• B. Visual inspection
• C. Dye-penetrant inspection
• D. Ultrasonic testing

Answer: (C)

Dye-penetrant inspection works by letting a colored dye seep into any surface-breaking cracks or defects, then drawing the dye out with a developer so you can see bleed-out on the surface under appropriate lighting. The key idea is that tiny defects create a pathway for the dye to enter, and when you remove the excess and apply the developer, the dye that’s trapped in the defect bleeds back to the surface and becomes visible. This method is used on nonporous materials like metals and many aerospace components, and it can use either a colored dye with normal lighting or a fluorescent dye viewed under UV light for greater sensitivity. This approach is distinct from magnetic particle inspection, which detects flaws in ferromagnetic materials using magnetic fields and iron particles; visual inspection, which relies on what can be seen without any penetrant or instrumentation; and ultrasonic testing, which uses sound waves to detect flaws inside a material. The question specifically mentions a colored dye and bleed-out on the surface, which points to dye-penetrant inspection.

Dye-penetrant inspection works by letting a colored dye seep into any surface-breaking cracks or defects, then drawing the dye out with a developer so you can see bleed-out on the surface under appropriate lighting. The key idea is that tiny defects create a pathway for the dye to enter, and when you remove the excess and apply the developer, the dye that’s trapped in the defect bleeds back to the surface and becomes visible. This method is used on nonporous materials like metals and many aerospace components, and it can use either a colored dye with normal lighting or a fluorescent dye viewed under UV light for greater sensitivity.

This approach is distinct from magnetic particle inspection, which detects flaws in ferromagnetic materials using magnetic fields and iron particles; visual inspection, which relies on what can be seen without any penetrant or instrumentation; and ultrasonic testing, which uses sound waves to detect flaws inside a material. The question specifically mentions a colored dye and bleed-out on the surface, which points to dye-penetrant inspection.