Blanca Luz Brum (1905–85) arrived in Montevideo in February 1933 with David Alfaro Siqueiros (1896–1974). She remained in that city until she had arranged for the founding of the CTIU (Confederación de Trabajadores Intelectuales del Uruguay) and the publication of the first issue of the organization’s magazine, Aportación. She then went to Buenos Aires to rejoin Siqueiros, who had been living there since May, organizing exhibitions and giving lectures prior to painting a mural (Ejercicio Plástico, a group effort) at the home of Natalio Botana, the owner of Crítica, a Buenos Aires newspaper. Siqueiros appears tense, partly because of the political harassment he was getting from the Mexican Embassy, and partly because of his difficult relationship with the Sociedad Amigos del Arte (where his exhibition was to be held), complicated by the pressure of countless invitations to meetings from his friends in Buenos Aires. Those friends included the Argentinean sculptor Luis Falcini, an active communist and one of Siqueiros’s main hosts during his visit; Alfredo Guido, the painter and member of the Círculo de Fomento a las Bellas Artes; the writers Raúl González Tuñón, Oliverio Girondo, Victoria Ocampo, and Pablo Rojas Paz, as well as the widow of the writer Ricardo Güiraldes, among many others. His letter reveals his desire to sell his work and the care he takes to say nothing that might offend the local bourgeoisie, a potential source of sales. He says he has already founded the Sindicato de Pintores as a first step toward the launch of the Confederación de Intelectuales de la Argentina.
The CTIU was founded in Montevideo in May 1933 on the initiative of David Alfaro Siqueiros and Blanca Luz Brum, his Uruguayan companion at that time. They had both arrived in Montevideo in late February 1933. Shortly after their arrival, in April, Siqueiros went to Buenos Aires, leaving Blanca Luz—together with a group of Uruguayans that included the painters Guillermo Laborde (1886–1940), Julio Verdié (1900–98), Norberto Berdía (1900–83), the poets Basso Maglio (1899–1961), Juvenal Ortiz Saralegui (1909–59), and Ildefonso Pereda Valdés (1899–1996)—to found the CTIU. This process involved arranging for the publication of the organization’s magazine, which was initially called Aportación but, several issues later, was renamed Movimiento.