What is the purpose of developers in liquid penetrant testing?

In liquid penetrant testing, developers serve a crucial role in enhancing the visibility of penetrant indications. After the penetrant has been applied to the surface and allowed to dwell, any penetrant that has entered surface defects will be drawn out to the surface during the development stage. The developer acts to draw the penetrant out of these defects and onto the surface, where it can be more easily seen.

The process of using a developer often leads to the formation of a contrasting color or a more pronounced indication, which greatly assists the technician in identifying flaws in the material being examined. This visibility is essential for accurate interpretation and assessment of the test results, allowing for appropriate corrective actions to be taken if necessary.