Critic and curator Alberto Sierra presents the work of Colombian sculptor John Castles in the catalogue to the exhibition Esculturas de John Castles/Pinturas de Marta Elena Vélez/ Serigrafías de Hugo Zapata held in April and May of 1979. The text discusses three important characteristics of Castles’s recent work: the economy of forms and use of large opposing rusty iron planes; the use of linear elements that “give a sense of fragility and clarify the sculptural work by means of gravity”; and the careful production process that enables an appreciation of the way lines and planes are projected in space. In closing, Sierra argues that, while the forms that Castles creates dominate the surrounding space, they grow more complex and rich when produced on a scale large enough to render “palpable the tension between forces.”

In this text, critic, gallerist, and curator Alberto Sierra (b. 1944) presents the works by John Castles (b. 1946) featured in the exhibition Esculturas de John Castles/Pinturas de Marta Elena Vélez/Serigrafías de Hugo Zapata held in April and May of 1979 at the Centro de Arte Actual in the city of Pereira. Sierra selected three artists who live in Medellín for a show representative of what was called the “Grupo de Medellín.” That group had participated in the exhibition Once antioqueños, organized by curator and critic Eduardo Serrano (b. 1939) at the Museo de Arte of Bogotá in 1975. The text describes three aspects of work that, due to its economic use of visual elements, partakes of the Minimalism of the seventies.  

Castles’s experience studying architecture at the Medellín campus of the Universidad Nacional of Colombia would prove essential to his approach to art. In the view of art historian Carmen María Jaramillo (b. 1958), major transformations in Colombian sculptural practices were spearheaded by a generation of artists that had studied architecture rather than art, among them figures like Hugo Zapata (b. 1945), Germán Botero (b. 1946), Alberto Uribe (b. 1947), Ronny Vayda (b. 1954), Félix Ángel (b. 1949), and Luis Fernando Peláez (b. 1945). 

John Castles became interested in certain aspects of Minimalism through North American artist Tony Smith (1912?80) and British artist Anthony Caro (1924?2013). His interest in reformulating the constructivist sculptural tradition in Colombia was largely due to Édgar Negret (1920?2012) and Eduardo Ramírez Villamizar (1923?2004). 

A critic, gallerist, and curator, Alberto Sierra has a degree in architecture from the Universidad Pontificia Bolivariana in Medellín. He founded Galería de la Oficina, also in Medellín, in 1974, which he has directed since its inception. He was the founder and curator of the Museo de Arte Moderno of Medellín. In 1978, he founded, and then directed, Re-Vista del Arte y la Arquitectura en América Latina (1978?81), a publication essential to the Colombian art scene. He has curated exhibitions for the Museo de Antioquia and the art collection of Suramericana de Seguros.