Keith Haring's work with Sumi ink on paper represents a fascinating aspect of his artistic output, showcasing his versatility and ability to engage deeply with different materials and techniques. Sumi ink, known for its use in traditional Japanese calligraphy, provided Haring with a medium that allowed for both the bold, graphic quality that characterizes much of his work and a level of spontaneity and fluidity.

One of the most significant pieces Haring created using Sumi ink is the "Amsterdam Notes," a sprawling work he crafted in 1986 during a visit to the Stedelijk Museum Amsterdam. This piece was created with high-quality Sumi ink and is notable for its departure from the vibrant colors and packed compositions that many associate with Haring. Instead, it features a range of detailed fantasy creatures spread more spaciously across the paper. Haring completed this work in one session, emphasizing the immediacy and instinctual nature of his creative process. The use of Sumi ink allowed for a dynamic range of line qualities, from bold and flowing to more delicate and faded, adding depth and texture to the work​ (Stedelijk Studies)​.

Haring's early explorations in Sumi ink can also be traced back to his formative years, with some of his large-scale ink drawings showcased in his early exhibitions. These works highlight his mastery over line and his ability to imbue simple forms with vibrancy and motion, often incorporating his signature elements like dripping paint, which add a raw, energetic quality to the pieces​ (artcritical)​.

Haring's use of Sumi ink aligns with his broader artistic philosophy of making art accessible and engaging for all. His approach to materials was not just about the aesthetic quality they could lend to his work but also about exploring their potential to communicate and resonate with a wide audience. The tactile quality of Sumi ink, combined with Haring's expressive, emblematic style, made for works that are deeply personal yet universally compelling.

The Keith Haring Foundation's archive offers a glimpse into the variety of Haring's work with Sumi ink, underscoring the breadth of his experimentation and the consistent innovation that marked his career​ (Haring)​.