Quantitative comparisons of the color of CuAs, CuSn, CuNi, and CuSb alloys

The colors of copper alloys are of particular interest in archaeology and can be characterized quantitatively and systematically. The CIELAB color system can determine different color parameters such as a*, b*, and L* by means of a spectrophotometer that describes the surface color. Additional information such as C* and h values can be calculated from these parameters which allows one to build a set of color-composition diagrams that connects chromaticity and alloy composition. With such data it is possible to estimate the color of prehistoric metal artifacts with similar chemical composition. A better understanding of the association between metallurgical composition and color will aid the research of prehistoric metalwork because choices in production and use of metal were likely influenced by this particular quality of metal.