Liquid Penetrant Testing Level 1 (PT-1) Practice Exam

Which technique is commonly used to ensure that excess penetrant has been removed before applying a developer?

1. Visual inspection in daylight

2. Scanning the surface with a blacklight

3. Touching the surface with bare hands

4. Using a high-intensity white light

The correct answer is: Scanning the surface with a blacklight

Using a blacklight to scan the surface is a widely accepted technique to ensure that excess penetrant has been removed before applying the developer. When the surface is inspected under a blacklight, the fluorescent penetrant becomes visibly apparent due to its ability to glow under ultraviolet light. This allows the technician to identify any residual penetrant that may not have been stripped away adequately during the cleaning process. The proper removal of excess penetrant is vital; if any penetrant remains on the surface, it can lead to false indications or masking of defects when the developer is applied. The glowing effect under the blacklight provides a clear confirmation that the surface is clean and ready for the next step in the testing process. This technique emphasizes the importance of thorough cleaning to achieve accurate and reliable results in liquid penetrant testing. In contrast to this method, other techniques like visual inspection in daylight may not reveal the residual penetrant effectively, especially if it’s a similar color to the surface being inspected. Touching the surface with bare hands can introduce contaminants or oils that may interfere with the test, and using a high-intensity white light may not provide the necessary sensitivity to identify the fluorescent characteristics of the penetrant.