Liquid Penetrant Inspection is used to detect surface-open indications such as cracks, porosities, and slag inclusions. The method involves applying a liquid dye to the surface, which penetrates into any cracks or imperfections. After a dwell time, excess penetrant is removed, and a developer is applied, drawing the penetrant out to create a visible indication.

Advantages:

• High sensitivity.
• Applicable to a wide range of materials.

Limitations:

• Only detects open surface indications.
• Relatively slow process.
• Requires thorough cleaning of the item.