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 |
|