What type of discontinuities is liquid penetrant testing capable of detecting?

Liquid penetrant testing is specifically designed to detect surface-breaking discontinuities in non-porous materials. This method relies on a penetrating liquid that is applied to the surface of the material. If there are any discontinuities—such as cracks, laps, seams, or voids—that are open to the surface, the penetrant can seep into these areas. After a certain dwell time, the excess penetrant is removed, and a developer is applied to draw the penetrant back to the surface, highlighting the presence of discontinuities.

The emphasis on "discontinuities open to the surface" is crucial, as this testing method does not have the capability to identify deep internal defects, which would require different techniques such as ultrasonic testing or radiographic testing. Additionally, while liquid penetrant testing can reveal discontinuities that may not be visible to the naked eye, it is limited to surface defects and does not address internal issues that are not exposed at the surface. Thus, option B accurately captures the primary ability of liquid penetrant testing in identifying relevant surface defects.