In addition to commissions for the clergy, Giotto also received commissions from private individuals. Right next to the choir are two chapels of the Bardi (adjacent to the choir) and Peruzzi with frescoes by Giotto. There is also an altarpiece in the chapel of Baroncelli in the southern transept. The Web Gallery of Art has good pictures of the Bardi chapel and the Peruzzi chapel and it also contains the schematic of the two fresco cycles.
Fresco technique and painting on the wall
In his handbook, ‘Il Libro dell’Arte’, Cennino Cennini explains to the artists how to work on a wall, i.e. in fresco. In chapter LVVII he describes how to apply the first layer of plaster, the arriccio, and
‘‘If you want to do some work, remember to roughen up the plaster and make it a little greasy. Then, when the plaster is dry, take the charcoal and draw and arrange according to the subject or the figures you have to draw. Take all measurements carefully, first set perpendiculars and then take half of the plane. Then set some perpendiculars and connect them horizontally. […] Then you make the composition of the subjects or figures with charcoal, as I have described. And always keep your zones to scale, and equal. Then take a small pointed hog bristle brush with a little ochre, without tempera, as thin as water, and trace your figures. Draw them in and shade them like you did when I taught you how to draw. Then take a bundle of feathers and wipe the charcoal from your drawing. Then take a little sinopel [red ochre; named after a city on the Black Sea: Sinopel] without tempera, and with a finely pointed brush you indicate the noses, the eyes, the hair and all the accents and outlines of the figures.Make sure that the proportions of these figures are correct, because this makes you familiar with the figures and helps you foresee what you will have to paint. Then start by making your ornaments or other things you want to make around it. When you have finished, take some of the lime mortar mentioned above, well prepared with spade and trowel so that it resembles an ointment. Then consider how much work you can do in one day, because you have to finish what you started.” Cited and translated from: Cennino Cennini, ‘Het handboek van de kunstenaar Il Libro dell’Arte’, Contact, Amsterdam/Antwerp 2001 (originele editie ca. 1400) blz. 105-107
This method of painting a fresco presented by Cennini is standard practice and is often described as a buon fresco. The underlayer is applied first, also known as the arriccio, and is around five centimetres thick. Depending on the weather, the drying of this layer takes about three to four months. The composition is then sketched, first with charcoal and finally with red ochre or sinopel. That is why these signatures on the first coat of plaster are called sinopias. At this stage, the drawing is often shown to the client to see if he is satisfied. Changes can easily be made at this stage and a second thin layer of approximately one centimetre is then applied. The lines drawn on the arriccio will be continued on the second wet layer of the half-day period. The size of the intonaco is quite different. It depends on ‘[…] how much work you can do in one day, because whatever you plaster you have to finish.’ ‘And let’s assume that in one day you have to do just one head, that of a saint or a young saint, like that of Our Most Holy Woman.
One example of this is seen in the architecture in ‘the Resurrection of Drusiana’ (Peruzzi chapel). Such a day’s work, or giornate, is necessary because the paint has to be applied to the wet intonaco because this is the only way to absorb the pigments in the lime layer. Since the limestone layer dries naturally, you have at best one day to paint it, but often only four or six hours. This isn’t easy at all. If it fails in that time, all you have to do is carve away the intonaco and apply another layer of lime. It is for good reason that there is the expression in Italian: ‘stare fresco.’ Which means as much as being in serious trouble.
Not every pigment can be applied to wet lime. Earthly colours are suitable, but a number of colours, including copper-based pigments, are not at all suitable. Blue always had to be applied dry, a secco. The pigment should then be painted on the dry lime with a medium such as tempera or glue. Such a binder on lime tends to eventually let go, while the pigments (without a line) on the wet lime are anchored deep in the lime layer. Even after a long time, the colours are still very fresh. This is what gave the technique its name: fresco. Gold and silver must also be applied later, so a secco. Nowadays this is clearly visible at the aureoles in the Peruzzi and the Bardi chapels. These are often severely damaged and some are entirely gone.
According to art historian Rona Goffen, the commissions for Giotto’s two fresco cycles were probably given simultaneously (in the 1320s) by both families (Goffen, R., Spirituality in Conflict: Saint Francis and Giottos Bardi Chapel, University Park, Pennsylvania State University Press, 1988 52-54). After his return to Florence in 1317 and his departure to Naples in 1328, Giotto had been given commissions left and right. The frescoes for the two adjacent chapels were probably painted one after the other. The cycle about St. Francis in the Bardi chapel is done in the usual way and is done wet in wet, otherwise known as buon fresco. Since the usual method, wet in wet, is not very sensible in the cold months, after his work in the Bardi chapel, Giotto painted the Peruzzi chapel on a dry layer of lime. Giotto opted for this slow but fast method because he needed time.
It is not just the inferior, but also faster technique, a secco, that Giotto used in the Peruzzi chapel, that indicates he was in a hurry. During the major restoration between 1958 and 1961, it appeared that at least five or six pairs of hands had been involved during the painting process.
The fresco cycles in both chapels, Bardi and Peruzzi, are severely damaged. The most severely damaged are the frescoes that were painted a secco. In the eighteenth century, fourteenth century art was no longer appreciated, so both chapels were painted over with a white brush. In the nineteenth century, Giotto’s frescoes were rediscovered and brought out again. Between 1958 and 1961 there was a major and drastic restoration. All later additions were removed, such as the small harp that Salome held in her hands. Nowadays you only see the original paint layer. Original parts that had disappeared were left open during the restoration.