Whitewash paint is a water-based paint composed primarily of water and lime. Chemical binders are typically added to improve the longevity and reduce the chalkiness of the mixture.
Whitewash paint adheres best to rough, porous surfaces. When applied, the paint forms a thin layer of calcium carbonate, which is the same substance that snail shells are made of. Binders that improve the quality of the paint include salt, flour, brown sugar or borax. Alum is also added to prevent the dry paint from rubbing off.
A common recipe for whitewash paint is five parts quicklime mixed with two parts of boiling water, combined with a mixture of three parts salt and one part water.