In the 1990s, Sol LeWitt's artistic practice saw significant developments, particularly in his transition towards more vivid and expressive uses of color and form. This period marked a noticeable shift from his earlier work, characterized by geometric abstraction and a more subdued palette. LeWitt began to explore curvilinear shapes and highly saturated colors, moving away from the strict geometric vocabulary that had dominated his work in the previous decades. This evolution can be seen in his wall drawings and sculptures from the late 1990s, which incorporate bright acrylic colors and free-form shapes, signaling a radical departure to something "not geometrical"​ (Wikipedia)​​ (The Metropolitan Museum of Art)​. One notable project from this period is "Sol LeWitt on the Roof: Splotches, Whirls and Twirls," an exhibition held at The Metropolitan Museum of Art in 2005, which showcased works created in the late 1990s and early 2000s. The exhibition featured "Splotch #15" and "Wall Drawing #1152 Whirls and Twirls," among others, highlighting LeWitt's engagement with non-geometric forms and his continued exploration of color. These works exemplify his growing interest in random curvilinear shapes and the use of bright, acrylic paints—a stark contrast to his earlier, more restrained works. The Splotches and the Whirls and Twirls wall drawing demonstrated vividly the artist's evolving aesthetic, marrying abstract forms with a bold, vibrant palette​ (The Metropolitan Museum of Art)​. Throughout the 1990s, LeWitt's work remained deeply conceptual, grounded in the belief that the idea behind the artwork was paramount. Despite these aesthetic shifts, his foundational approach to art—emphasizing the concept over the physical execution—remained consistent. LeWitt's practice continued to challenge traditional notions of artistic authorship and the role of the creator, often employing teams of assistants to execute his designs based on precise instructions. This methodological approach underscores the democratic and collaborative spirit that defined much of LeWitt's work, distinguishing him as a pioneering figure in conceptual and minimal art​ (Wikipedia)​​ (The Art Story)​​ (www.wikiart.org)​. LeWitt's contributions during the 1990s further cemented his legacy as an innovator, unafraid to evolve and experiment with new forms and media. By embracing change and pushing the boundaries of minimalism and conceptualism, LeWitt continued to influence the trajectory of contemporary art, leaving an indelible mark on the art world.