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The Alloys: Architectural Bronze and Other Copper Alloys

To a metallurgist, alloys of copper and zinc are known asbrasses and those of copper and tin are known asbronzes. Artists and architects however, commonly use the term bronze to describe a variety of copper alloys that contain little or no tin. These copper and zinc alloys are known as bronzes because of their appearance and weathering characteristics. The table below lists the characteristic and common names of some of the more popular bronze, brass and other copper alloys and their common names. For bronze architectural ornament as well as bronze statuary and sculpture the most often used bronze is statuary bronze, an alloy of copper and zinc. ASTM and SAE developed a Unified Numbering System for metals and alloys, with "C" indicating a copper alloy.

Alloys based on ASTM and SAE# Composition   Color
      Natural Weathered
Architectural Bronze C38500 57% Copper
3% Lead
40% Zinc
  Reddish Yellow

Russet Brown to Dark Brown
Commercial Bronze C22000 90% Copper
10% Zinc
  Red Gold Brown to Gray-Green Patina in Six Years
Red Brass C23000 85% Copper
15% Zinc
  Reddish Yellow Chocolate Brown to Gray-Green Patina
Cartridge Brass C26000 70% Copper
30% Zinc
  Yellow Yellowish, Gray-Green
Muntz Metal C28000 60% Copper
40% Zinc
  Reddish Yellow Red-Brown to Gray-Brown
Silicon Bronze C65500 97% Copper
3% Silicon
  Reddish Old Gold Russet Brown to Finely Mottled Gray-Brown
Nickel Silver C74500 65% Copper
25% Zinc
10% Nickel
  Warm Silver Gray-Brown to Finely Mottled Gray-Green
Leaded Nickel Silver C79600 45% Copper
42% Zinc
10% Nickel
2% Manganese
1% Lead
  Warm Silver Gray-Brown to Finely Mottled Gray-Green