Ed Ruscha's "Stains" series from 1969 is a compelling exploration of materials and form, pushing the boundaries of traditional art mediums. This portfolio, comprising seventy-six mixed media stains, showcases Ruscha's experimental approach to art-making, using a variety of substances to create stains on paper. These substances ranged from organic materials like egg yolk, beer, and salad dressing to more unconventional ones such as turpentine and gunpowder, with one of the stains being the artist's own blood on the inside back cover of the box housing the portfolio​ (MoMA)​​ (National Galleries)​.

This work reflects Ruscha's interest in the mundane and the overlooked, transforming accidental or often ignored occurrences, like stains, into subjects of artistic exploration. The choice of materials highlights his fascination with the physicality of art and the act of creation itself, emphasizing the process over the finished product. This series is a part of Ruscha's broader engagement with artist books, which were revolutionary in their simplicity and conceptuality, blending photography, text, and unconventional materials to challenge the viewer's perception of art and its value​ (National Galleries)​​ (Sotheby's Institute)​.

"Stains" is significant not only for its content but also for its format. Presented in a portfolio box, this work aligns with Ruscha's exploration of the artist's book as a medium, considering the book itself as an artwork. This approach resonated within the conceptual art movement, where the idea behind the artwork often dictated its form, emphasizing structure, serial imagery, and an interest in everyday objects and occurrences​ (MoMA)​​ (National Galleries)​.