With the decadence of classic art some portion of the process seems to have been lost, and the use of pounded travertine was substituted for white marble; but, as the _bassi-relievi_ of the early Renaissance were mostly decorated with colour, this was not important. The ground colours seem generally to have been laid on whilst the stucco was wet, as in fresco, and the details heightened with tempera or encaustic colours, sometimes with accessories enriched in gilt "gesso" (of which hereafter). Many remains of these exist, and in the Nineteenth Winter Exhibition of the Royal Academy there were no less than twelve very interesting examples of it exhibited, and in the South Kensington Museum are some few moderately good illustrations of it.
It was not, however, until the sixteenth century that the old means of producing the highly-finished white stucchi were rediscovered, and this revival of the art as an architectonic accessory is due to the exhumation of the baths of Titus under Leo X. Raphael and Giovanni da Udine were then so struck with the beauty of the stucco work thus exposed to view that its re-use was at once determined upon, and the Loggia of the Vatican was the first result of many experiments, though the re-invented process seems to have been precisely that described by Vitruvius. Naturally, the art of modelling in stucco at once became popular: the patronage of it by the Pope, and the practice of it by the artists who worked for him, gave it the highest sanction, and hardly a building of any architectural importance was erected in Italy during the sixteenth century that did not bear evidence of the artistic craft of the stuccatori.
There has just (Autumn, 1889) arrived at the South Kensington Museum a model of the central hall of the Villa Madama in Rome, thus decorated by Giulio Romano and Giovanni da Udine, which exemplifies the adaptability of the process; and in this model Cav. Mariani has employed stucco-duro for its execution, showing to how high a pitch of finish this material is capable of being carried. Indeed, it was used by goldsmiths for the models for their craft, as being less liable to injury than wax, yet capable of receiving equally delicate treatment; and Benvenuto Cellini modelled the celebrated "button," with "that magnificent big diamond" in the middle, for the cope of Pope Clement, with all its intricate detail, in this material. How minute this work of some six inches diameter was may be inferred from Cellini's own description of it. Above the diamond, in the centre of the piece, was shown God the Father seated, in the act of giving the benediction; below were three children, who, with their arms upraised, were supporting the jewel. One of them, in the middle, was in full relief, the other two in half-relief. "All round I set a crowd of cherubs in divers attitudes. A mantle undulated to the wind around the figure of the Father, from the folds of which cherubs peeped out; and there were many other ornaments besides, which," adds he, and for once we may believe him, "made a very beautiful effect." At the same time, figures larger than life, indeed colossal figures, were executed in it, and in our own country the Italian artists brought over by our Henry VIII. worked in that style for his vanished palace of Nonsuch. Gradually, stucco-duro fell into disuse, and coarse pargetry and modelled plaster ceilings became in later years its sole and degenerate descendants.