A visible dye indication typically appears as which color?

In liquid penetrant testing, visible dye indications often appear as a red color against a white background. This is primarily because the red dye is formulated to contrast sharply with white surfaces, making any indications of defects easier to see. The visibility of the red dye is enhanced against the white background, allowing inspectors to identify cracks and other discontinuities effectively. It is critical in penetrant inspection that the indications are easily discernible, and red against white serves this purpose well due to its brightness and the strong contrast provided.

The choice of red as the color for the indication also has practical advantages in terms of industry standardization and visibility under various lighting conditions, ensuring that inspectors can reliably find and evaluate defects.