In 1960, de Castro presented a number of his Active Objects at II Exposição Neoconcreta, Rio de Janeiro, and became associated with the neo-concrete artists. This series offered an inventive solution to the fundamental propositions put forward by the group’s ideologist, the Brazilian poet and critic, Ferreira Gullar. In his signal 1959 essay “Theory of the Non-Object” Gullar argued that the modernist–constructivist desire to distill and subsequently end painting was finally reaching its inevitable conclusion.  For Gullar, this process, intensified by Kazimir Malevich and Piet Mondrian, culminated in the neo-concrete non-object—a new notion of the art object inserted directly into space without a frame or pedestal. Subsequently, the non-object was not only liberated from the delimiting structures of the frame and pedestal, but also from the verbal designations imposed by language. Challenging classifications according to pre-existent categories within art history, it suspended any a priori knowledge favoring the “primal –total-experience of the real.”   De Castro, now among the neo-concrete group, had the most consistent interpretation of the legacy of Constructivism which sought to abandon easel painting and embrace modes of industrial production. And industrial design he did, from the textiles for Rhodia to logos and graphic identities for large industrial conglomerates.