What is one advantage of postemulsifiable methods compared to water washable methods?

Postemulsifiable methods indeed offer easier control of sensitivity compared to water washable methods, making them advantageous in many testing applications. This control stems from the fact that postemulsifiable penetrants can be adjusted to achieve desired sensitivity levels based on the specific requirements of the inspection being performed.

In postemulsifiable testing, the emulsifier is applied after the penetrant has had time to penetrate the flaws in the material. This allows for the flexibility to modify the sensitivity of the penetrant to either detect smaller defects or adapt to different types of materials and surface conditions. Adjusting the concentrations and types of emulsifiers in these methods can enable better fine-tuning for the testing requirements.

In contrast, water washable methods do not offer this level of sensitivity adjustment because the penetrant's performance is more chemically fixed once applied. Therefore, choosing postemulsifiable methods provides a strategic advantage when detailed sensitivity control is necessary for various testing conditions.