What is the most common type of contaminant found in fluorescent penetrant fluid?

The most common type of contaminant found in fluorescent penetrant fluid is water. This is primarily due to the fact that fluorescent penetrant testing is highly sensitive to the cleanliness of the surfaces being inspected. Water can introduce significant interference because it can prevent the penetrant from properly adhering to the surface and infiltrating any potential defects.

In practice, excessive moisture can lead to false indications or missed flaws, as water can wash away or dilute the penetrant. Ensuring that the surfaces are dry and free from water or moisture before applying the penetrant is crucial for accurate testing results.

Other contaminants, such as oil, solvent, and dust, while they can also affect the performance of the penetrant, are less frequently encountered compared to water. Water's physical properties and its ubiquitous presence in various environments make it a prevalent concern in ensuring the integrity of the testing process.