Combined analysis of enamelled and gilded glassware from Frederick II Castle at Melfi (Italy) to identify technology and raw materials

A group of enamelled and gilded glass objects, coming from Melfi Castle (PZ - Italy) from an area dated to the period between the end of the 12th and the last quarter of the 13th century, offered the opportunity to closely investigate this technology with the aim of understanding the raw materials and the procedures employed to realize the objects and their precious decorations. Optical microscopy, scanning electron microscopy coupled with energy dispersive X-ray spectroscopy, Raman spectroscopy, laser ablation-inductively coupled plasma-mass spectrometry and X-Ray photoelectron spectroscopy were used to observe and analyze the glass, the enamels, the gildings and their mutual relations. The bulk of the objects resulted a soda-lime glass, while the enamels are lead-based 'soft' enamels or soda-lime glass; the palette of pigments employed to obtain their colours included iron III oxide and minium for red, lazurite and/or cobalt for blue, lead-tin-antimony pyrochlore solid solution oxide (yellow) plus cobalt for green, manganese oxides for black and calcium phosphate for white. Results obtained for gilding, in particular stratigraphy and morphology, suggest the use of the so called 'liquid gold'.