Which of the following is a disadvantage of the post emulsifiable penetrant process?

The post emulsifiable penetrant process involves an additional step where an emulsifier is applied after the penetrant has been allowed to dwell on the test piece. This emulsifier is crucial because it helps to remove excess penetrant from the surface while allowing penetrant that has entered any discontinuities to remain, thus enhancing detection. However, the requirement for this extra processing step can be seen as a disadvantage, as it adds complexity, time, and the potential for additional handling errors during the inspection process.

In contrast to the other choices, where items such as re-processing capabilities or sensitivity to specific types of discontinuities are mentioned, the core issue with the post emulsifiable process is directly tied to the extra step involved. This step can affect throughput and efficiency in an inspection cycle, making it a notable disadvantage within the context of the entire testing process.