Penetrant testing (PT) is a rapid, simple, inexpensive, and sensitive nondestruc­ tive testing (NDT) method. It allows the inspection of a large variety of materials, component parts, and systems for discontinuities that are open to the surface; these discontinuities may be inherent in the original materials, result from some fabrication process, or develop from usage and/or attack by the environment. Because PT is portable, it is often used in remote locations .