What is the type of NDE test that involves coating a part with dye and then a developer?

The type of Nondestructive Evaluation (NDE) test that involves coating a part with dye followed by the application of a developer is known as Liquid Penetrant Testing. This method is particularly effective for identifying surface-breaking flaws such as cracks, voids, and other discontinuities.

In this process, the part is first cleaned to remove any grease, dirt, or other contaminants that might interfere with the test. The dye penetrant is then applied, which seeps into any surface-connected defects. Once the dye has had adequate time to dwell, a developer is applied, which draws the penetrant out of the flaws and onto the surface, creating a visible indication that can be easily seen and interpreted.

Liquid penetrant testing is widely used because it requires minimal equipment and can be applied to a variety of materials, making it a flexible and efficient testing method in many industries.