Motion pictures . The basic elements of preservation are inspection, repair and cleaning. Video copies have been made by archives to preserve film, but the best course is to preserve film as film. Film cannot be considered preserved if the master is not in a public institution. The Film and Television Archives Advisory Committee is a group through which archives decide who should collect what.
Low humidity is the most important aspect of preservation.
Still pictures . Baked enamel on storage equipment may emit destructive gases if the enamel was not baked right originally. Some people use commercial underground storage facilities, which are all right, as long as you make sure they are actually protecting your photographs. Actually look at their vaults and inspect their hygrothermograph records. There are 8 or 10 underground storage companies in this country.