What is generally considered a drawback of using excessively cold penetrant materials?

Using excessively cold penetrant materials is known to negatively impact the effectiveness of penetration into surface defects. Cold temperatures can cause a decrease in the viscosity of the penetrant, which affects its ability to seep into small cracks or pores. This is critical because one of the primary functions of liquid penetrant testing is to ensure that the testing medium can effectively fill these discontinuities to reveal any defects during the inspection process. If the penetrant does not adequately penetrate the flaws, it will result in missed indications of defects, thus compromising the integrity of the testing.

In contrast, while the other options may address concerns related to penetrant performance under certain conditions, they do not specifically highlight the core issue of penetration effectiveness at cold temperatures. The ability of the penetrant to properly infiltrate into surface irregularities is essential for the overall success of the testing procedure.