Another possibility is movement of the pigment caused by the properties of certain materials to absorb a liquid, or the use of surface tension of the liquid. An example might be my work “The In-Visible” of 1990. I buried a pouch with an aggressive dye into foundations of a building, which due to its permeability slowly released pigment into its surroundings. It resulted in a scary stain which at the time spread over the sidewalk and into the basement of an adjacent building. As the painting gradually bled, the intensity of the color gradually faded until the stain completely disappeared.
The In-Visible, 1990
variable dimensions
red pigment