During the excavation campaign of 1992, a large Valencia majolica plate, decorated in blue and lustre was found in the so-called "butto" (dump) of the castle of Monreale. The artefact lacks a part of the outer peripheral band.

It presents a small shallow centre whose sides are strongly inclined towards the outside, the flat outer part has a thickened and rounded rim, and a flat bottom.

The inner surface (fig. 1) is decorated in lustre with the plant motif of anillos con discos and in its centre there is depicted a blue bird (perhaps a peacock or a hawk) facing to the left, with great legs, a short and curved beak, a tuft on the head and a long tail which reaches the edge of the plate.

The outside of the artefact (fig. 2) is decorated in lustre, with a stylised plant motif consisting of three leafy elements enclosed in irregular circles drawn with a thin line.

Fig. 1 - Valencia majolica plate with central zoomorphic figure in blue; inner surface (photo by Unicity S.p.A.).

Fig. 2 - Valencia majolica plate with central zoomorphic figure in blue; outer surface (photo by Unicity S.p.A.).

The artefact’s making proves the skill of the craftsmen-potters of Paterna and Manises, centres located just a few kilometres away from Valencia which, between the fourteenth and the seventeenth centuries, were specialised in the production of ceramics decorated with the characteristic golden and blue glazing (fig. 3) sought after throughout Europe, where they were imported by merchants from Pisa, Genoa, Milan and Venice.

The technique used was that of the "metallic lustre", characterised by the iridescence of the ornaments, widely tested in the East from the ninth century, but also well attested in the Iberian Peninsula.

After being made on the lathe and dried, the vases were subjected to a first firing at a temperature of 850-900 °C, in order to obtain the so-called "bisque", in other words, the ceramic body without any coating. Subsequently, the surface of the object was coated with a vitreous enamel, opacified by the addition of tin oxide, generally white.

The surface thus obtained, after proper drying, could be painted with metal oxide dyes, thanks to which it was possible to obtain various colours: cobalt for blue, copper for green and manganese for purplish brown.

At this point the artefact was subjected to a second firing, during which the vitreous paint and the colours fused adhering to the ceramic body. In order to make the lustre decoration, a mixture of metal salts (silver oxide or copper) and clay diluted with vinegar was applied to the ceramic, and a third firing was necessary.

This was carried out, however, at a low temperature of about 600 °C, to prevent the excessive heat from evaporating the metal film. Small furnaces in which it was possible to regulate the draft, as the air needed to be reductant, that is deprived of oxygen, were therefore used for this purpose.

To achieve this, it was necessary to close the openings and use smoking substances (green wood, sugar, etc.) which prevented the metals from oxidising.

After cooling, the surface had to be scrubbed to remove any residues of clay and smoke and to bring out the lustre. Silver produced a yellow or greenish colouring, while copper a yellow, orange or brown one.

Fig. 3 - National Art Gallery of Cagliari, bowl from the so-called "Pula Foundation" decorated in blue and lustre; second quarter of the fourteenth century (from http://www.pinacoteca.cagliari.beniculturali.it/imagePreview.php?id=229).

Among the most significant artefacts decorated in blue and lustre, those which make up the "Pula Foundation" should be included (fig. 4).

This consists of 58 ceramic artefacts dating back to the first half of the fourteenth century, found in 1869 in Pula, in the province of Cagliari.

During the expansion and refurbishment works of the road leading to Monte Granatico a storage room dug into the ground was discovered (a rectangular pit of 1.20 X 1.00 and 0.80 metres deep; fig. 5) which contained pottery produced in Valencia, Pisa-Liguria, Majorca and Sicily.

This is the most important find of Hispanic-Moorish ceramics ever occurred in Sardinia. These finds are currently kept at the National Art Gallery of Cagliari.

Fig. 4 - National Art Gallery of Cagliari, bowl from the so-called "Pula Foundation" decorated in blue and lustre; second quarter of the fourteenth century (from http://www.pinacoteca.cagliari.beniculturali.it/imagePreview.php?id=405).

Fig. 5 - The pit with the ceramics from the so-called "Pula Foundation" drawn by F. Nissardi.