Paint is two things: pigment (colored powder, often ground minerals) and a binder that holds it and sticks it to a surface. Change the binder and you change everything: how fast the paint dries, how you can work with it, and how it looks centuries later.
| Medium | Binder and surface | What it does |
|---|---|---|
| True (buon) fresco | Pigment in water, brushed into wet lime plaster | Becomes part of the wall as the plaster sets; very lasting; must be painted fast, one day's patch (giornata) at a time |
| Fresco secco ("dry") | Pigment with glue or egg, on dry plaster | Easier to correct, but flakes off more easily |
| Egg tempera | Pigment in egg yolk, usually on a wooden panel coated with gesso | Dries in minutes; built up in fine strokes; crisp and luminous |
| Oil | Pigment in drying oil (often linseed), on panel or canvas | Dries slowly; can be blended and laid in thin, transparent glazes |
| Mosaic | Small cubes (tesserae) of stone or glass set in mortar | Glitters and lasts; a picture made of pieces |
| Encaustic | Pigment in hot wax | Rich, lasting color; used for ancient portraits |
Key idea
Why it works
Looking closely: Fra Angelico's Annunciation. An angel with striped wings bows to a seated young woman in a simple porch of slender columns and arches. The colors are pale and clear, the forms simple, the background garden flat and quiet. That matte, chalky clarity is typical of true fresco. It was painted at the top of a staircase in a friars' convent, so the friars saw it every time they climbed to their rooms.
Looking closely: The Last Supper's surface. Leonardo wanted to work slowly and blend like a panel painter, so he did not paint true fresco. He used tempera and oil on a dry wall. The paint began flaking within decades. What you see today is the result of many repairs and a long restoration finished in 1999.
Worked example: Which medium?
- Fresco sets within a day, so no.
- Tempera dries in minutes and is built in small strokes, so blending is hard.
- Oil stays workable for days and can be glazed.
Answer: Oil paint.
Common mistake