Emulsion paint consists of tiny polymer particles within which the pigments are trapped. The particles are suspended in water, then as the paint dries the particles fuse together creating a film of paint on the wall. Once this happens the polymer can’t be resuspended in water, which is why you can’t wash a water-based emulsion paint back off the wall once it has dried.
But how does it break down?
Pigments - 25 per cent
Titanium dioxide is used for white, iron oxide for yellows, reds and browns, chromium oxide for greens, and carbon is used for blacks.
Solvent - 45 per cent
Nearly half of emulsion paint is made up of water.
Binders - 25 per cent
Acrylic or epoxy polymers surround the pigments and help them to bind to the wall.
Other additives - 5 per cent
These include biocides to stop algae and fungi growing on your walls.