"PET Compounds"

      Bronze is made by smelting copper and tin together. When bronze is cast for use in statues, it contains between two and 20% tin, while bells use a higher percentage of tin: 15-20%. Additives are included when the bronze needs to be more workable, harder, or easier to cast. For example, phosphorous is added to harden bronze for use in tubing and various machine parts, while lead is included to make bronze take more readily to casting. Bronze is often confused with brass, an alloy of copper and zinc, but the two alloys have different properties and are used for different things. In addition, bronze is much harder than brass.
      Bronze has several properties that make it valuable in industrial applications. The first is that the metal causes minimal friction, making it highly useful for machine parts and other applications that involve metal on metal contact, such as gears. Bronze is also non-sparking, so it is often used to make tools for use in combustible environments. The resonance of bronze also makes it ideal for use in casting bells.
       One of the more unique properties of bronze is the natural patina that forms on it, turning the bronze a dark, dull color. This patina is actively encouraged with most bronze, because it provides a protective layer, preventing oxidation below the surface of the bronze. Before being shipped, most bronze is coated with a thin layer of lacquer to protect the metal and the patina, making the metal very easy to care for.


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(Copper)

Copper Facts

Copper is man's oldest metal, dating back more than 10,000 years. A copper pendant discovered in what is now northern Iraq goes back to about 8700 B.C.

Some things never change! Ten thousand years ago, cave dwellers used copper axes as weapons and tools for survival. Today, high tech surgeons save lives and precious blood by using copper-clad scalpels. The copper conducts an electric current that heats the scalpel to make it self-cauterizing.

The first copper deposit worked extensively in America (by non-native Americans) is located in Granby, Connecticut. It was operated from 1705 until 1770.

Pure copper's melting point is 1,981ºF (1,083ºC).

Brasses and Bronzes are probably the most well-known families of copper-base alloys. Brasses are mainly copper and zinc. Bronzes are mainly copper along with alloying elements such as tin, aluminum, silicon or beryllium.

A leaded yellow brass, C36000, also known as Copper Alloy 360 is so easy to machine, it is the benchmark standard for metals machinability.

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