Mechanism of coloration in copper-stained float glass

Abstract Copper staining was applied to a commercial float glass and to a Colburn glass, resulting in green and yellow colors, respectively. Such glass was investigated with optical spectroscopy and X-ray diffraction analysis. It was observed that the colors of copper-stained float glass comprised three kinds of extinction structures in the transmittance spectrum located around the wavelengths of 460 nm, 560 nm and 600 ∼ 660 nm. The first two were attributed to the intrinsic absorption of metallic copper colloids while the last was ascribed to the scattering by the metallic copper colloids. Cuprous oxide was considered to be an ineffective colorant. A coloration model for the copper-stained float glass was presented in terms of the variation in size of metallic copper particles.