Brass is any alloy of copper and zinc; the proportions of zinc and copper can be varied to create a range of brasses, each of which has unique properties. Brass is a substitutional alloy. It is used for decoration for its bright gold-like appearance; Brass has a yellow color, somewhat similar to gold. It is relatively resistant to tarnishing, and is often used as decoration and for coins. Brass has likely been known to humans since prehistoric times.
Brass has higher malleability than copper or zinc. The relatively low melting point (900–940 °C depending on composition) of brass and its flow characteristics make it a relatively easy material to cast. By varying the proportions of copper and zinc, the properties of the brass can be changed, allowing hard and soft brasses.
Today almost 90% of all brass alloys are recycled. Because most brass is nonmagnetic, it can be separated from ferrous scrap by passing the scrap near a powerful magnet. Brass scrap is collected and transported to the foundry where it is melted and recast into billets. Billets are later heated up and extruded into the right form and size.
The copper in brass makes brass germicidal, via the oligodynamic effect. For example, brass doorknobs disinfect themselves of many bacteria within eight hours [2]. This effect is important in hospitals, but useful in many contexts.
Brass has a combination of strength, corrosion resistance, and formability that will continue to make it a useful material for many applications in the foreseeable future. Brass also has an advantage over other materials in that most products made from brass are recycled or reused, rather than being discarded in a landfill, which will help ensure a continued supply for many years.
CLEANING BRASS
Tarnish on unlacquered brass can be removed with a commercial cleaner or a homemade one: Saturate a cloth or sponge with household vinegar or lemon juice, sprinkle it with salt and thoroughly rub the tarnished object. Be sure to rinse the brass extremely well and buff to a shine. Lacquered brass is easier to clean. It needs only to be wiped with a dry cloth.
Showing posts with label BRASS ARTEFACTS. Show all posts
Showing posts with label BRASS ARTEFACTS. Show all posts
BRASS - The Golden éclat
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