Examining the enamel on the Aldrevandini beaker
The Aldrevandini beaker is a very early example of enamelled glass produced in Venice from the late thirteenth to early fourteenth centuries. The main output of this style of object was in the fifteenth and sixteenth centuries. Heraldic emblems and scenes featuring animals or people in coloured enamel on transparent glass are typical decorative themes.
This beaker is unusual in that it is complete and in a pristine state of preservation. Other examples of the so-called Aldrevandini group survive only as fragments.
British Museum scientists using a scanning electron microscope to study the beaker have found that two types of enamels were used. The first type is made from pigments and colourless glass melted together to make a coloured glass which was crushed for application as enamelling. The second type is made from crushed colourless glass mixed with pigments and was not melted before application.
The technology of enamelling on glass is known to have its origin in the centres of the Middle East where, amongst other items, enamelled glass lamps were produced. However, unlike many of the Middle Eastern examples, on the Venetian vessels the main areas of colour such as the infilling of foliage and backgrounds of heraldic devices are on the insides, while the outlines and borders are on the outer surfaces – a simple solution to the problem of colour separation. This, along with the relative coarseness of the enamelled decoration, seems to distinguish the technique of the Aldrevandini glasses from those of the main Middle Eastern centres.
The method of making the Aldrevandini enamels as well as the compositions of the glass are very similar to contemporary enamelled Islamic glass. This suggests some transfer of knowledge and materials from the Middle East to Venice must have taken place, though the craftsmen making these enamelled glass wares in Venice clearly did not have the same confidence in applying the enamels. This argues against the view that Middle Eastern glass workers were working in Venice at the time.