Studies on the Renaissance Venetian <em>Rosetta</em> Beads through Chemical Analyses and Recipes of Muranese Glassmakers

The term rosette (little roses) first appeared in reference to glass beads and cane slices in Venetian documents dated 1482. The term has indicated chevron glass beads and cane slices applied to glass objects (millefiori decoration). These beads were obtained from segments of drawn glass canes presenting in their section consecutive circular and star-pattern polychrome layers. The invention of the rosetta beads is attributed to Maria Barovier, daughter of the famous Muranese glassmaker Angelo. The production of these canes in Murano has continued almost uninterrupted to the present day and not only in Venice. This study reports on quantitative chemical analyses (micro X-ray fluorescence or wavelength dispersive X-ray microanalysis) of the individual colored layers of five genuine Venetian archaeological rosetta beads and fragments of canes dated sixteenth to early seventeenth century. The analyses evidence that the base-glass composition as well as colorants and the opacifier are in the tradition of Renaissance Venetian glass. They correspond to a recipe for rosetta cane reported in a treatise of an unknown Muranese. In contrast, three recipes for rosetta cane of a treatise dated to the second half of the eighteenth century evidence a quite different scenario: new raw materials and a new opacifier.