Which of the following factors can lead to incorrect defect detection in PT?

A rough surface finish can significantly affect the effectiveness of liquid penetrant testing. In PT, the surface condition of the test item plays a critical role in how well the penetrant can flow into defects like cracks or porosity. If the surface is rough, it may not allow the penetrant to properly seep into subsurface defects, potentially leading to missed indications. A rough texture can also trap penetrant on the surface rather than allowing it to enter flaws, which may create false positives or obfuscate actual defects.

In contrast, using a high-quality penetrant, having a clean and dry surface, and following the manufacturer's instructions are factors that typically enhance the effectiveness and reliability of the test. High-quality penetrants are designed to have optimal flow and retention properties, a clean and dry surface allows for proper adhesion and penetration without interference from contaminants, and adherence to manufacturer's instructions ensures that the testing process is carried out in a manner that maximizes the potential for accurate defect detection.