What is the long-term effect of dried paint accumulating inside the ferrule?

Correct answer: The bristles spread and the tip loses its shape

The governing concept is brush maintenance and ferrule care. Dried paint near the ferrule hardens between the bristles, forcing them apart and preventing the hairs from returning to a controlled point. Thus option D is correct: the brush spreads and loses its useful tip. The buildup does not improve handle flexibility, paint brightness, or water capacity; instead, it reduces precision and control over time.