Which statement about Level 3 and Level 4 penetrants' brightness is true?

• A. They maintain 70% brightness
• B. They maintain 50% brightness
• C. They maintain 90% brightness
• D. They maintain 10% brightness

Answer: (A)

Brightness retention is a characteristic of fluorescent penetrants that describes how much of the initial brightness remains after development and during viewing. Level 3 and Level 4 penetrants are the brighter end of the spectrum, and they are specified to keep about 70% of their original brightness. This level of retention provides strong visibility of indications under normal inspection lighting without over-saturating the view, which helps detect tight or subtle flaws. The other percentages would imply either too dim or too intense a brightness for these high-brightness penetrants, so 70% is the correct standard for Level 3 and Level 4.