Michael I stated clearly in my first post about using SILVER BOX to shield MULTIPLE ROLLS OF film: "The best way to shield film form X ray is put them in a sterling silver container. Silver is the provide the best protection against x ray, much better than lead; a silver box of 1 mm thickness can stop 99.5% if xray. (Not silver plated ) "(posted 8471 days ago)The aborption factor Mu of silver =60.4 and Mu(lead)-52.2 is scientific facts, just like specific weights etc.