Early Russian glasses: Composition, manufacture, nature of color

The early Russian glasses produced from 12th to 14th century, based on PbO-SiO2 and K2O-PbO-SiO2 systems, are a special artistic and productive phenomenon in European medieval culture. Being prepared from sand and washed ash and colored by manganese and copper compounds, they showed a wide variety of colors due to variability of concentrations of lead and chromophores. Here we discuss the color of specific examples of Russian glasses and their modern replica. It is shown that the coloring of lead glasses is affected not only by d-d transitions in metal ions but also by the shift of the fundamental edge caused by the metal ion acting as dopant. The blue coloration of lead glasses achieved by introduction of copper and manganese was a specific receipt developed by Russian glassmakers due to lack of cobalt ore. The inefficiency of manganese for discoloration of lead glasses is also shown. A brief history of Russian glassmaking in 12th–14th centuries is also given.