How Paint Dries

When you paint a wall or a picture, the paint starts as a liquid and slowly becomes solid. Paint is a mixture of pigments for color, a binder to hold it together, and a liquid to make it spreadable. As the liquid part dries up, the pigment and binder form a tough, colorful film.

Evaporation Drying

Water-based paints like latex dry by evaporation. The water in the paint slowly leaves and goes into the air. As the water evaporates, the tiny binder particles move closer together. They eventually merge into a continuous film that traps the pigment particles. This is why you need good air flow to help paint dry faster.

Chemical Drying

Oil-based paints dry through a chemical reaction with oxygen in the air. This process is called oxidation. The oil in the paint reacts with oxygen and forms a hard, tough film. This takes longer than evaporation, which is why oil-based paints take much longer to dry. But the result is often a harder, more durable finish.

Fun Facts

• Some oil paintings by old masters took weeks or even months to dry completely.
• The color of paint can change slightly as it dries because the binder becomes transparent.
• Cave paintings made over 30,000 years ago used natural pigments mixed with animal fat as a binder.

Did You Know?

The famous Mona Lisa was painted with oil paints. Leonardo da Vinci worked on it for about four years. Oil paints dry so slowly that he could blend colors smoothly and create the painting's famous soft, glowing look!