By around 1550 the della Robbia workshop's secret glaze recipe was all but lost. This relief can almost be seen as the technique's last gasp. Here, an artist who worked in the sophisticated and graceful sculptural style typical of the later sixteenth century sought to add color through the application of glazes. With no access to the della Robbia recipe, he returned to the traditional practice of the maiolica painter, from which the della Robbia technique had originally grown. The low lead content meant the glaze was too viscous to achieve the desired effect; large areas of the Virgin's white robe show imperfect flow and poor attachment of the glaze. The artist also applied two layers of glaze-first using a white glaze, over which he applied a second glaze-a maiolica technique that resulted in more transparent and less pure color tones, as in the green of the background.

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