Liquid Penetrant Testing is widely used to find leaks in materials, such as metals, plastic and ceramics. This technique uses a liquid to be drawn into a clean surface breaking flaw by capillary action. After a period of time called the “dwell” excess surface penetrant is removed and a developer applied. This acts as a blotter.  It draws the penetrant from the flaw to reveal its presence.

Advantages

• Highly sensitive to small surface crack and flaws.
• Very little equipment is needed
• Large areas can be inspected quickly and at low cost.
• Parts with complex shapes are inspected routinely.
• Aerosol spray cans make penetrant materials very portable.
• Low cost method

Disadvantages

• Only surface breaking defects can be detected.
• Only areas with nonporous surfaces can be inspected.
• Pre-cleaning is necessary as contaminants can mask defects.
• The inspector must have direct access to the surface being inspected.
• Surface roughness can affect inspection sensitivity.
• Proper disposal is required.