From 1990, Mariani begins to work from the subject of drapery that he is passionate about, and creates in his works known as I Piombi a stylized and geometrized idea of this subject matter. The drapery loses all true form, and the works crystallize in straight lines that look to affirm a more idealistic, symbolic vision. In 2011, the exhibition Le Vesti di Saturno is held in the prestigious halls of the Medici Gallery in Palazzo Medici-Riccardi in Florence. The solo exhibition entitled Recent Works-Piombi followed in 2013 in the Baroque spaces of the Sala San Ignazio in Arezzo and later that year, the anthological exhibition Umberto Mariani-Opere 1967-2013 (catalogue edited by Allemandi) takes place in the Chiostri di San Domenico in Reggio Emilia. At the beginning of 2019, the artist was awarded by the Centro Studi Grande Milano at Palazzo Isimbardi, the Grandi Guglie honor, for his role as an ambassador of Milanese culture in the world.