Urban representation and chromatic research in the tradition of Vatican micromosaics

The so-called micromosaico (minute mosaic) is a singular form of urban representation, that has comtributed, since the end of XVIII century to spread throughout Europe, by production of jewelry and precious articles, the image of monuments and cities of Italy such as destinations of the Grand Tour. This technique obtained the citizenship in Vatican by the establishment in 1587 of the mosaic school of the Reverenda Fabbrica di San Pietro, with the task of decorating the interior of the basilica and replaying in a non-perishable form the pictorial heritage. The objective of imitating painting had requested a specific technical research, aimed at obtaining an almost infinite chromatic range of enamels, able to simulate the results of chromatic modulation obtained by brush. Despite this great technical skill, at the end of XVIII century the completion of the works of reproduction threatened to leave unemployed the mosaicists of the school, transformed by institution of the Studio del Mosaico Vaticano. It happened, however, that two of the most skilled and renowned of them, Cesare Aguatti and Giacomo Raffaelli, devised the so-called technique of "spun enamel", consisting in spinning of the vitreous enamel surface of the mosaic tiles, so as to obtain thin bars (1 millimeter in cross section). These could be segmented into tiles to compose tiny mosaics for inserting in wide range of items to serve as Italienreise souvenir: furnishings, such as coffee tables or fireplace coatings, or much smaller articles, such as snuff-boxes or jewelry. The ichonografic themes, which initially consisted mainly of classical antiquities, have gradually expanded to include depictions of the most popular urban places of Rome and then, since XIX century, even of other cities - Milan, Naples, Venice – where, in the Napoleon’s Era, they tried to export the know-how of the Roman Studio and, in parallel, developing their chromatic experimentation. The beginning phase of the micromosaic, coinciding with the last quarter of XVIII century, is dominated by the Giacomo Raffaelli’s personality, whose palette already included 872 different shades from18 basic colors, among which predominates quantitatively the flesh-colored (over 800 bars) and the green color, with 77 different shades. The second phase, has been caracterized by the Antonio Aguatti’s invention of the so-called malmischiato, gradient tiles obtained by spinning of bars in variegated colors, that brings the art of micromosaic to its full maturity. The third phase started from the Michelangelo Barberi’s invention of the colori a soffio (colours by blowing), obtained by using in the spinning a weld lamp used by goldsmiths. These bars show colours with a particular vividness and a chromatic spectrum much broader than that obtained in furnace. So, if throug time the production of engravings and urban views has provided to mosacists a rich iconographic base for inspiration, we must not believe that this has been a mere work of reproduction or virtuosity of craftsmanship, because the transition from the incision in black and white to the composition mosaic, introduces the color - which, in the extremely small size of the final image, is fully in charge of the perspective composition - an absolutely original factor, wich can now boast a range of 28,000 different color variations, the so-called munizioni (ammunitions) still in the possession of the Studio del Mosaico Vaticano