What is the main purpose of using a developer in the liquid penetrant testing process?

The primary purpose of using a developer in the liquid penetrant testing process is to draw out the penetrant from surface discontinuities, making them visible for inspection. When the penetrant is applied to a surface, it seeps into any flaws or cracks present. The developer is then applied over the surface, and it acts by absorbing the penetrant that has been trapped in these discontinuities.

This action creates an indication that can be easily seen, usually through a change in color or contrast on the surface, depending on whether a fluorescent or color contrast penetrant is used. By drawing out the penetrant, the developer ensures that the indications are enhanced, allowing for better detection and evaluation of potential defects. This step is critical in achieving accurate and reliable test results in liquid penetrant testing.