Love how this one aged: it used to be b/w. I made it by applying heat + water to shopping receipts paper (no paint or ink) and called it "Calor Scripturam", which is just a fancy way of saying "heat writing" in Latin.
Photo by Gert Jan van Rooij, courtesy Upstream Gallery Amsterdam.
Heat-sensitive shopping receipt paper, mounted on canvas.120 × 80cm / 47.2 × 31.5″detail