Got a roll of new carbon tape, hand rub off powder phenomenon, what happened?

1. The carbon belt used by the customer is kept at a low ambient temperature and for a long time, resulting in this phenomenon.

2. The carbon strips purchased by customers may be wax-based or general-purpose mixed bases, so this phenomenon occurs.

3. This batch may not be detected when the carbon belt purchased by the customer leaves the factory, and the factory quality inspection department needs to detect whether there is imagination in this batch.