Dry dust back
The simplest method of treating a whole roll of film is the 'dry dust back’. This uses a soft velvet cloth made from either cotton or polyester. Before using, check that the cloth is free from dirt of any sort.
Holding the clean cloth gently with the fingers as shown in Fig 12.2, wind the film carefully through. The cloth should be rearranged frequently so that a fresh, clean portion is being used.
This method is only suitable for very light dirt and requires great care not to scratch the film. After using the cloth, wash it with a mild, non-perfumed soap and ensure that it is thoroughly dry before using it next.