The Agfa-Book of Photographic Formulae, Ed #265994

Pinholes or minute white specks are very common, and are caused by small particles of dust settling on the plate or film while it is being handled in loading the plate holder, mak ing the exposure, or developing, the developer thereby being prevented from properly acting upon the sensitive film. To avoid pinholes, carefully dust the plates, both when loading and just before developing, using either a camel's hair brush or a soft velvet covered pad, both of which must be kept clean and dry. The camera should also be frequently and carefully dusted inside.