Toscana
A novel technique in the history of mosaics: the Annunciation in Pisa Cathedral
There is a mosaic in the Cathedral of Pisa that is unique in the world: it is an Annunciation, attributed to Lippo Memmi, which adopts a technique not hitherto found elsewhere. Everything you need to know about this fascinating work.
By Sara Chirico | 10/03/2025 17:31
Entering Pisa Cathedral through the main door, we are greeted by the large apsidal mosaic that stands out imposingly at the end of the nave. In the center, Christ Pantocrator by Francesco da Pisa stands out, while on the right we find the figure of Saint John by Cimabue and on the left the figure of the Virgin by Vincino da Pistoia. Continuing the visit, on the apses of the transepts, we can glimpse two other wall mosaics that often go unnoticed. Both feature the Virgin, portrayed in theAnnunciation in the north transept and theAssumption in the south. The latter two works have been dated between 1321 and 1345, thus executed in the years when Vincino was completing the figure of the Virgin in the main apse. However, while the attribution of the major mosaic is certain, the two minor mosaics have no clear author. Historically they have been attributed to Francesco Traini, but more recently some scholars have assigned them to Lippo Memmi (Siena, ninth decade of the 13th century - 1356), passing also an interesting attribution hypothesis to a young Simone Martini.
Both mosaics have been partially covered by 16th-century monuments, which now obstruct their full view from below. Although they are less attractive than the main mosaic, where Cimabue's hand captures the attention, they should not be overlooked for the unique technical information they contain and instead deserve much attention. Thanks to the care that theOpera della Primaziale Pisana devotes to its heritage, it was possible to carry out a careful restoration of the mosaic of the Annunciation, and restoration work is now underway for that of the Assumption as well. The interventions on the mosaics, followed by the writer, are not limited to conservation alone but also include the fundamental phases of investigation and study. In this case, the work has allowed for an in-depth study of the execution techniques that are the peculiarity of these works.
Indeed, among the materials used for tessellation are colored glass paste tesserae often cut into unusual shapes (such as elongated tesserae that recall the pattern of pictorial brushstrokes), stone tesserae, terracotta tesserae, mirrors and curious stucco tesserae. The latter, created from colored mixtures shaped into square or rectangular cubes, were inserted into the mortar along with the other tiles. The stucco tiles belong to the ancient phase of the mosaic; they are not restoration tiles. This certainty is given by the bedding mortar in which they are inserted.
The composition of the figures in the mosaic is conceived in the synchronous use of all these materials: each has a specific function and serves to meet precise aesthetic requirements. The stucco tiles, very small in size, were mainly used to compose the more refined and accurate areas of the faces. On the mosaic of the Annunciation, in fact, 24 portraits are represented, and as a result of the restoration it was possible to recover and reread the features of these characters that were partly illegible before the intervention. Cleaning made it possible to admire again the refinement of their execution, in which stucco tiles predominate.
But why create tiles that are less valuable and durable than the materials traditionally used? The answer to this question can be traced by observing the color range of the vitreous mixtures that were available to the mosaicists who worked on them under the commission and design of the author. Missing from the colors available is the pink of the flesh tones, which was a difficult color to achieve with the glass pastes: traditionally, in fact, the pink of the skin was executed with stone or terracotta tesserae that could come close to the requirements sought. In this case, stone tesserae are used for faces and hands, but in addition to them, stucco tesserae were devised that allowed the color range of pink tones to be expanded. These tesserae were easy to obtain, made from readily available and workable materials (lime, oils, and pigments), so the craftsmen of the time took advantage of this resource to further increase their palette, creating not only more rosy tones but also orange, brown, yellow, ochre, green, and opaque white tones that were missing in the glass impasti.
This invention, which to date is traced only in these two mosaics, and which has not yet been found in other works, makes the two artifacts a technical unicum so far documented in the history of mosaics. Another curious aspect are the semi-transparent glazes located on the faces of the figures that go to delicately accentuate volumes and shadows; these are semi-transparent pictorial brushstrokes composed of oils and a few pigments that go on top of the tesserae. Some analytical elements lead us to speculate that these are retouches born with the conception of the work. Elongated glass tesserae that recall brushstrokes, stucco tesserae made of lime, oils and pigments, and semi-transparent pictorial glazes on the tessellato-these unusual technical elements hint at a world in which mosaic merges with painting. The artists to whom they are attributed are known as painters, and the technical devices used in these two works are the result of a fusion of worlds, the world of mosaic and the world of painting. Indeed, we are in a historical period, in which painting is beginning to take over from mosaic, and here we see an example of this influence.
The mosaic of the Annunciation is now visible, the scaffolding on the north transept has been removed, and the work has moved to the south transept. Visiting the Cathedral, one can admire again, with perhaps a somewhat different look, these magnificent works as well.
