[1]: 7 [2]: 13 However, the arc of Ha's practice from the 1960s to the present is more fundamentally characterized by his wide explorations of materiality and ways of challenging the conventions of art making.
Whereas his experiments with what is conventionally characterized as gestural and geometric abstraction served as a preparatory ground for his engagement with materiality, his involvement with the art group AG (est.
His works have often been contextualized within exhibitions and writings on Dansaekhwa, but his early experimentalism forms a vital part of 1960s and 1970s art in Korea.
Works dating between 1962 and 1965 indicate Ha's layering broad brushstrokes as well as his manipulation of the wet paint to inscribe gestures or incisions upon it, or embrace its liquid quality as it dripped down the canvas.
[1]: 9 Two works from 1965 demonstrate Ha's choice to lacerate the canvas, perturbing its paint-covered fibers and exposing their individual threads.
[1]: 27 Ha's Naissance series, made beginning in 1967, carried forward a lacerating technique to meet mat-like woven areas of canvas and obangsaek hued-paints within the context of geometric compositions.
Notably, in the White Paper on Urban Planning series, the art historians Kyung An and Yeon Shim Chung have found multiple layers of allusions to the rapidly transforming Seoul of the late 1960s, from the dancheong patterns of the ancient Korean architecture (then becoming recognized and conserved as national heritage) to discussions of urbanization playing out on the pages of Space magazine.
[4]: 9 [1]: 9 [2]: 13 [5]: 26 [6]: 17 While some art historians argue that Ha attempted to extend his painting beyond two-dimensionality, into the spaces of sculpture and even architecture,[3]: 125 [2]: 22 the art historian Kim Mikyung went so far as to call for an interpretation of Ha's early work that looks beyond the terms and categories of Euro-American modernism: "Regarding his transition in the space of one year from 1965, critiques training up from Western traditions might put it as a sharp turn from Informel tendencies towards geometric form and distribution or Op art….
[1]: 28 For the works he presented in the AG exhibitions, Ha abandoned the brush to experiment with juxtaposing other materials and objects in ways that, as the curator Yoon Jin Sup has described them, emphasized contrast.
Ha's Work 72(B) (1972), shown in the third AG exhibition,[3]: 26 consists of springs that extend horizontal from the left and right sides of pictorial plane, then meet in the middle and spill forward in a mane-like mass.
Consistently, scholars, curators, and critics have addressed the complexity of the above artworks' relationship to the political atmosphere and increased policing of free speech during the Park Chung Hee regime.
In particular, the art historians Kim Mikyung and Joan Kee have proposed that, respectively, the repressive atmosphere of and ubiquity of military presence during these years inescapably permeated these works.
[2]: 28 For a third work—created to join works by the artists Lee Ufan and Kim Kulim to collectively form the group "Terme relationnel" within the seventh Paris Biennial—Ha poured wet cement into the sacks that originally packaged it, where it dried.
"[4]: 24 Similarly, Phil Lee has argued that "what is significant is to discover not only Korean (Asian) beauty but also the universal resonance embodied in [Ha's] works.