What is the term for a painting done on wet plaster on a wall or ceiling?

A painting technique characterized by applying pigments directly onto freshly laid, wet lime plaster on a wall or ceiling is known as fresco. The word "fresco" itself is derived from the Italian adjective meaning "fresh," aptly describing the crucial role of the wet plaster in this artistic method. As the water-based pigments are applied, they are absorbed into the damp plaster. Then, as the plaster dries and sets, a chemical reaction occurs, permanently binding the colors to the wall. This integration makes the painting an inseparable and highly durable part of the architectural surface.

This ancient and enduring art form has roots dating back to civilizations like the Minoans of Crete and the Romans, with examples found in places such as the Palace of Knossos and Pompeii. However, fresco painting reached its zenith during the Italian Renaissance, becoming the preferred method for large-scale murals due to its monumental style and impressive longevity. Its durability is a significant advantage, allowing many masterpieces to survive for centuries, offering a unique glimpse into the past.

Among the most celebrated examples of fresco art are Michelangelo's breathtaking ceiling in the Sistine Chapel and Raphael's "The School of Athens" in the Vatican. The technique demands immense skill and speed from the artist, as work must be completed before the plaster dries, often requiring artists to tackle sections in a single day, known as a "giornata." This challenging yet rewarding process has resulted in some of the most iconic and visually stunning artworks in human history.