Fresco (Italian: “fresh”) is the traditional medium for painting directly onto a wall or ceiling. It is the oldest known painting medium, surviving in the prehistoric cave mural decorations and perfected in 16th-century Italy in the buon fresco method. The cave paintings are thought to date from about 20,000–15,000 bce. Their pigments probably have been preserved by a natural sinter process of rainwater seeping through the limestone rocks to produce saturated bicarbonate. The colors were rubbed across rock walls and ceilings with sharpened solid lumps of the natural earths (yellow, red, and brown ocher). Outlines were drawn with black sticks ...(100 of 16294 words)