The 19th century painting "El Juramento de los 33 Orientales" by painter Juan Manuel Blanes, that depicts the historic landing of the 33 Orientals, militant revolutionary group of the Oriental Band (or the "Eastern Bank" of the Río de la Plata) led by Juan Antonio Lavalleja in the beach of the Agraciada in 1825, is being intervened with the aim of recovering its original colors. The edition documents the restoration process, detailing the treatments and applied techniques of the painting, a great symbol of the national artistic heritage. The investigations in course on the materiality of the pictorial work are included.