Overview

Fresco is the most durable form of painting in history. Unlike oil paint, which sits on the canvas, fresco becomes part of the wall. The pigment chemically bonds with the wet plaster (calcium carbonate). This is why Roman frescoes from Pompeii still look bright red after 2,000 years, while Leonardo’s Last Supper (painted on dry wall) is flaking off.

Core Idea

The core idea is Carbonation. It’s a chemical reaction. You mix pigment with water and apply it to wet lime plaster (calcium hydroxide). As the plaster dries and absorbs carbon dioxide from the air, it turns back into limestone (calcium carbonate), trapping the color inside the stone crystal.

Formal Definition

A technique of mural painting executed upon freshly laid (“fresh” = fresco in Italian) lime plaster.

  • Buon Fresco: True fresco (wet plaster). Durable.
  • Fresco Secco: Dry fresco. Painting on dry plaster with a binder (egg, glue). Less durable, used for touch-ups.

Intuition

Imagine tattooing a wall. If you draw on your skin with a pen, it washes off. If you tattoo ink into the skin, it stays forever. Fresco is a tattoo for architecture.

Examples

  • The Sistine Chapel Ceiling (Michelangelo): The most famous fresco. He had to paint it lying on his back (actually standing with his head back) while the plaster was wet. He could only paint a small section (giornata or “day’s work”) at a time before it dried. You can still see the seams between the days.
  • The School of Athens (Raphael): Located in the Vatican. It shows the perfect, luminous colors that fresco allows.
  • Diego Rivera: The Mexican muralist revived fresco in the 20th century to paint massive political histories on public buildings, believing it was the “people’s art” because it couldn’t be bought by private collectors.

Common Misconceptions

  • It’s just painting on a wall: Graffiti is painting on a wall. Fresco is a chemical process.
  • You can fix mistakes: You can’t. Once the plaster dries, the color is set in stone. If you mess up, you have to chip the plaster off with a hammer and start over.
  • Sinopia: The underdrawing sketched on the rough plaster layer to guide the artist.
  • Cartoon: The full-scale paper drawing used to transfer the design to the wall (by pricking holes and dusting charcoal through them).
  • Lime Cycle: The chemical cycle (Limestone -> Quicklime -> Slaked Lime -> Limestone) that makes fresco possible.

Applications

  • Church Decoration: Before literacy, frescoes were the “Bible of the Poor,” telling stories on the walls.
  • Public Art: Because it is permanent and monumental, it is ideal for government buildings and memorials.

Criticism / Limitations

  • Climate: Fresco hates humidity. It works great in dry Italy. It fails in damp Venice or England (the water makes the plaster rot).
  • Immobility: You can’t move a fresco (unless you cut the wall out). It is tied to the building.

Further Reading

  • Cennini, Cennino. The Craftsman’s Handbook (Il Libro dell’Arte). 1400. (The medieval manual on how to do it).
  • Vasari, Giorgio. The Lives of the Artists. 1550.
  • Meiss, Millard. The Great Age of Fresco. 1970.