Which of the following characteristics does not apply to liquid penetrant testing?

Liquid penetrant testing is a widely used non-destructive testing method designed to identify surface discontinuities in materials. The essence of this method is to utilize a penetrant that seeps into surface-breaking defects, making it possible to reveal flaws that might not otherwise be visible.

The first characteristic mentioned, which suggests that this method can accurately measure the depth of a crack or discontinuity, is not applicable to liquid penetrant testing. While it is effective at detecting the presence of surface flaws, it does not provide quantitative measurements regarding the depth of these flaws. The penetrant can illuminate whether a flaw exists, but it cannot gauge how deep that flaw penetrates into the material. The depth of a crack typically requires a different approach or method, such as ultrasonic testing, which is designed to evaluate subsurface features and their dimensions.

In contrast, liquid penetrant testing does accurately detect surface discontinuities, is suitable for use on non-porous materials, and is known for its sensitivity to small flaws. This technique is particularly valuable in various industries, especially in metals and other solid materials where surface integrity is crucial. Its effectiveness in revealing very fine cracks makes it a popular choice for quality assurance in fabrication and maintenance operations.