The function of a developer in Liquid Penetrant Testing is to:

In Liquid Penetrant Testing (PT), the developer plays a crucial role in enhancing the visibility of defects that may be present on the surface of a part. After the penetrant has been applied and allowed to dwell, the developer is then applied on top of the penetrant. The function of the developer is to absorb any excess penetrant that remains on the surface, which creates a contrast that makes the indications of subsurface flaws more easily visible.

This process aids in drawing the penetrant out of the defects into the developer layer, thereby highlighting potential cracks, porosity, or other surface anomalies. By absorbing residual penetrant and providing a contrasting background, the developer makes it easier to see the resulting indications, which are crucial for accurate inspection and assessment of the component's integrity.

The other options describe functions that do not align with the primary role of the developer in PT. The developer does not aim to completely remove the penetrant or change its color; rather, it works in conjunction with the penetrant to amplify the visibility of defects during inspection. Additionally, while preparing for subsequent inspection phases is important in overall testing procedures, it is not the specific function of the developer itself.