What is the ideal type of developer for use on very smooth surfaces with fluorescent penetrants?

The ideal type of developer for use on very smooth surfaces, especially in conjunction with fluorescent penetrants, is a wet developer. Wet developers are designed to provide a thin film of developer on the inspected surface, allowing for good penetration and visibility of defects highlighted by the penetrant.

When applied to smooth surfaces, the wet developer helps ensure an even coating, which is critical for effective inspection. The fluid nature of wet developers aids in their distribution across the surface, enabling the developer to interact effectively with any penetrant residues that may be present. This interaction is essential for enhancing the visibility of discontinuities under ultraviolet light, which is used in conjunction with fluorescent penetrants for non-destructive testing.

In contrast, powder developers can create a less uniform application on very smooth surfaces, potentially leading to inadequate visibility of defects. Liquid developers may not be as effective in creating the necessary contrast or might not adhere as well to smooth surfaces. Dust developers, like powder developers, also risk uneven distribution and may not yield optimal results when precision is required, particularly with smooth surfaces needing a fine finish.