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 antimicrobial efficiency tests include: The registrations are based on studies supervised by EPA which found that copper alloys kill more than 99.9% of disease-causing bacteria within just two hours when cleaned regularly (i.e., the metals are free of dirt or grime that may impede the bacteria's contact with the copper surface). To attain the EPA registrations, the copper alloy groups had to demonstrate strong antimicrobial efficacies according to all of the following rigorous tests: The alloy groups tested and approved were C11000, C51000, C70600, C26000, C75200, and C28000. The EPA registration numbers for the six groups of alloys are as