Which color combination is primarily used in magnetic particle testing for visibility?

In magnetic particle testing, the visibility of the magnetic particles is crucial for detecting surface or near-surface defects in ferromagnetic materials. The color combination used in this method plays an important role in enhancing visibility against the substrate being inspected.

The combination of red and black is particularly effective because the red particles stand out sharply against a black background, making it easier for inspectors to see any irregularities or defects. Red particles are commonly used as they have good contrasting properties, allowing them to be easily distinguished. The black background helps to absorb excess light and reduce glare, which can further enhance the visibility of the red particles.

In contrast, other color combinations may not provide the same level of contrast or clarity needed for effective inspection. For instance, while black and white can be visible, the lack of vibrant contrast might not be as effective in highlighting flaws as the red and black combination.