Liquid Penetrant

Inspection of Surface Integrity

Penetrant Testing (PT), also known as Liquid Penetrant Inspection (LPI), Dye Penetrant, and Fluorescent Penetrant Inspection (FPI), is a reliable, efficient, and versatile test method for revealing potential flaws that are open to material surfaces.

Liquid Penetrant testing is capable of revealing cracks, seams, fusion discontinuities and other critical flaws that normal visual inspection may not detect.

Because higher stress loads are generally concentrated on the outer surfaces of components, an enhanced surface inspection process such as Liquid Penetrant testing is crucial to flaw detection and failure prevention.

Baker Testing can perform Liquid Penetrant inspection both on-site and at our testing labs using brightly visible, color contrast dyes and highly sensitive fluorescent penetrant.


  • Weld Inspection
  • Casting Inspection
  • Tools Inspection
  • Testing of in-service components

Liquid penetrant inspection can be used to inspect all metal alloys and many other materials for flaw detection and surface integrity as a cost saving, quality control, code conformance, or pre-machine screening process.  

Versatile Testing

Specialized, high-sensitivity fluorescent or visible dyes are applied to clean, uncoated, non-porous surfaces. Capillary action draws penetrant dye into surface flaws. After sufficient “dwell” time, excess penetrant is removed from surfaces and a developer is applied to aid the penetrant “bleed-out.”

Developer sprays and powders also add contrast to brightly colored dyes to reveal otherwise undetectable cracks and other defects that could cause product or component failures.

Evaluation of parts tested by liquid penetrant can prove code acceptance or failure, surface integrity, and ensure reliable service of materials exposed to stress and wear.

Liquid Penetrant inspection is often used in conjunction with, and in support of, other NDT methods at Baker Testing Services laboratories and in on-site field applications.

Multiple combinations of test materials, application methods, and sensitivity levels support an array of power generation, welding, foundry, engineering, construction, and manufacturing applications.

Qualified PT Technicians

  • Technicians with over 40 years of experience in Liquid Penetrant Testing and other NDT methods to provide expert inspection for most any application.
  • Experienced Level II and Level III personnel are trained and certified to ASNT-TC-1A, CP-189 and MIL-STD-410/NAS 410 requirements.
  • Large and small parts or components can be inspected in accordance with ASME, AWS, MIL-STD, AMS, ASTM codes and specifications as well as customer specific requirements.
  • Baker Testing’s qualified procedures conform to ASTM and Military specifications to fit the needs of the customers in many diverse fields and applications.
  • Veriforce Operator Qualified (OQ)