For "whitewashing" refering to omissions of problems, issues, or facts, see Censorship.

Whitewash is a type of inexpensive paint made from slaked lime (Calcium hydroxide, or Ca(OH)₂) and chalk (whiting). Other additives have historically included milk, flour, salt, glue, water glass and soap. Whitewash cures through a reaction with carbon dioxide in the atmosphere to form calcite.

It is usually applied externally, for example, to whitewash a fence, as Tom Sawyer was famously made to do in Mark Twain's The Adventures of Tom Sawyer. Occasionally, it is colored and used on interiors, such as hallways of apartment buildings. Whitewash is especially effective on adobe like materials because it is absorbed easily and the resulting chemical reaction hardens the substrate.

Lime wash is pure slaked lime in water. It produces a unique surface glow due the to refraction of calcite crystals.

The word "whitewash" is sometimes used (particularly in politics) to describe a cover-up or a deliberate downplaying of a problem, for example the Hutton Inquiry. Its first reference dates back to 1762 by a Boston Evening Post article. In 1800, the word was first used in a political context, when a Philadelphia Aurora editorial said that "if you do not whitewash President Adams speedily, the Democrats, like swarms of flies, will bespatter him all over, and make you both a speckled as a dirty wall, and as black as the devil."