The two workers in this image, employees of the Monson-Maine Slate Company, are sanding slate slabs from the quarry for retail sale.

The two sanding drums on each of the belts are fed through smaller drums overhead. The entire mill ran on a series of belts from a main shaft, as can be seen on the two vertical belts attached by the ceiling. There was no dust collection system for the slate dust but water was often used during the process to help keep dust to a minimum.