The 16th century Palazzo di Bianca Cappello (Via Maggio, 26) sports one of the best examples of a type of decoration known as sgraffito (scratchwork), which is produced by scratching the surface of a plastered facade to reveal the coloured plaster beneath.
A wall was first given a rendering coat (rinzaffo) to cover and fill the holes and joints in the rough masonry. It was then coated with a layer of dark-coloured plaster (arricciato). A coat of white lime wash was applied to the arricciato before the latter was dry.
The surface was now ready for the sgraffito to be applied. A sketch was made on the white layer to scratch the outlines of the design. Using a stylus, the top white layer was scratched away to reveal the darker layer below. The contrasting colours of the light outer surface and the dark lower layer enabled figures or patterns to appear.
As a technique for decorating the exterior of a building, sgraffito has two advantages over the traditional fresco: it requires less skill and it is more weather-resistant.
The facade of the Palazzo di Bianca Cappello was painted between 1574 and 1579 by Bernardino Poccetti (1548-1612), who was also known as Bernardino delle Facciate (Bernardino of the Facades).
Poccetti created a complex and detailed tapestry of allegories and allusions. For instance, the four white swans and the Latin motto NON MINUS CANDORE QUAM CANTU ET VATICINIO SACER (no less white than sacred song and prophecy) refer to the virtues of the mistress of the house, whose first name means white in Italian.
Bianca Cappello was the mistress, and later the wife, of Francesco de' Medici (b.1541/r.1574-87), grand duke of Tuscany, hence the presence of the Medici coat of arms.