When performing a dye penetrant inspection, what must be done prior to applying the developer?

Before applying the developer in dye penetrant inspection, thoroughly washing the part is essential. This step is crucial to ensure that any contaminants such as dirt, grease, or previous coatings are removed from the surface. Contaminants can hinder the penetration of the dye into any surface cracks or defects, ultimately affecting the accuracy of the inspection results.

By washing the part, you create a clean surface that allows the penetrant to seep into any flaws effectively, ensuring that the inspection is reliable and effective. This step directly contributes to the overall quality and integrity of the inspection process.

Other methods such as heating the part, polishing the surface, or applying oil would not assist in creating the optimal conditions for the penetrant to adhere and function correctly.