In 1930 the Mexican government gave him the assignment to found a painting school in Taxco, Guerrero. In 1931 he began attending the lithography workshop of Emilio Amero together with other artists including Carlos Orozco Romero, Carlos Mérida, and Francisco Dosamantes, and he has produced numerous lithographs dating from that year. In 1932 he became an art teacher working for the Mexican Secretariat of Public Education and he completed two al fresco murals at two separate public schools.
His first one man show (both graphic arts and painting) was in 1932 at the Sala de Arte de la Secretaría de Educación Pública. The following year he exhibited in Chicago.
Zalce was a very active member of politically-progressive groups including the Liga de Escritores y Artistas Revolucionarios (League of Revolutionary Writers and Artists, 1933-dissolved in 1937), and in 1937 he was one of the cofounders of the Taller de Gráfica Popular (Workshop of the People's Graphics), together with other important artists including Leopoldo Méndez (1902-1969), Pablo O'Higgins (1904-1983), and Luis Arenal (b. 1908).
Between 1937-1950, Zalce painted four murals on the walls of schools in the states of Colima, Puebla, Michoacán, and in Mexico City. In 1945 he completed one of his most famous works, the portfolio Estampas de Yucatán after spending four months in southern Mexico. In 1948 he had a major exhibition at the Instituto Nacional de Bellas Artes that was subsequently offered in his home state of Michoacán at the Museo Michoacano de Morelia.
In 1950 he became the director of the Escuela Popular de Bellas Artes de Morelia (sponsored by the University of Michoacán) and the Escuela de Pintura y Artesanías de Morelia (sponsored by the Instituto Nacional de Bellas Artes). He has worked primarily in Morelia from that date. In the 1950s he completed major commissions including the Chamber of Deputies of the State of Michoacán and the City Hall of Morelia.
In 1960, seventeen of his prints formed part of the collective
exhibition of the TGP, "450 años de lucha. Homenaje
al pueblo mexicano." In 1981, the Museo de Arte Moderno
de Chapultepec (Mexico City) had a major retrospective celebrating
50 years of his work in which were exhibited 200 works of painting,
sculpture, textiles, drawings, and graphics.