Bell metal metal used is a high-tin alloy of copper and tin with approximately a 4:1 ratio of copper to tin (78% copper, 22% tin). This is a much higher tin component than that used in statuary bronze. A range of percentages of tin content can vary from 20 to 26%, depending on the founder who has arrived empirically at their own alloy ratio. It has been found that increasing the tin content increases the decay time of the bell strike, thus making the bell more sonorous. Taking into consideration overall properties, such as tensile strength, hardness, wear resistance, cast quality, sound,
Antimicrobial copper-alloy touch surfaces in rooms with copper touch surfaces were significantly lower than in rooms without copper surfaces. "Staphylococci" were the most predominant microorganism isolated and copper was effective in reducing the "Staphylococci" microbial burden. Further studies regarding the clinical implications of copper's intrinsic ability to reduce microbial burdens in hospitals are being planned. Researchers from the Kitasato University School of Medicine conducted antimicrobial studies of "S. aureus", "E. coli", and "P. aeruginosa" on various Japanese copper alloy coins and on copper alloy plates. The microbes were strains from hospital environments. Copper and its nickel-silver, cupronickel, and brass alloys were found to kill