Non-Destructive Testing (NDT) Practice Test

To achieve optimal results, how should the developer be applied in terms of thickness?

1. Thick coat to absorb penetrant

2. Lightly coated to provide contrast

3. Evenly thick coating across the surface

4. No specific thickness required

The correct answer is: Lightly coated to provide contrast

The optimal application of the developer in non-destructive testing (NDT) significantly impacts the effectiveness of the penetrant testing process. A lightly coated developer provides the right balance needed to create contrast without overwhelming the penetrant indications. The purpose of the developer is to draw out the penetrant from any flaws or discontinuities and enhance visibility against the surface it is used on. When the developer is too thick, it can obscure the indications by creating a layer that disrupts the contrast necessary for clear interpretation of the results. Conversely, if there is no developer or an overly thin application, the penetrant may not be adequately drawn out from the flaws, making them difficult to detect. Therefore, a lightly coated application is preferred to promote adequate interaction between the penetrant and the developer, allowing for enhanced visibility of any defects while maintaining the integrity of the inspection process.