In a post-emulsification fluorescent process, which method is NOT acceptable for emulsifying the penetrant?

In the context of a post-emulsification fluorescent process, the method of emulsifying the penetrant is critical to ensuring proper inspection results. The correct answer indicates that brushing the emulsifier on the part is not an acceptable method. This is because brushing can lead to uneven application of the emulsifier on the surface of the part. An inconsistent layer can result in inadequate emulsification, leading to poor visibility of any flaws detected during the inspection.

Dipping the part into an emulsifier solution, using a spray to apply the emulsifier, and submerging the part in emulsifier are methods that allow for a more uniform application. These techniques ensure that the emulsifier adequately coats the surface and penetrates into any defects or irregularities, facilitating more reliable and effective non-destructive testing. Thus, the significant concern with brushing is that it does not guarantee the same level of coverage or consistency compared to the other methods.