As bold as brass

The expression ‘As bold as brass’ is one of several English phrases that use repetition for emphasis. Examples of this are ‘beck and call‘, ‘helter-skelter‘, ‘topsy-turvy‘ etc. The repetition in ‘bold as brass’ comes from the fact that one meaning of the word ‘brass’ is ‘effrontery; impudence; unblushingness’, that is, ‘boldness’.

That meaning of brass is also called on in the expressions ‘brazen faced’ (bold and without shame) and ‘brass neck’ (cheekiness or effrontery).

The link between boldness and brass was commonly made in 17th century literature.

The English Catholic priest used it in 1608 in a pamphlet criticising Jesuits:

Yet heere the lying impudent Jesuite telleth vs boldly without blushing, (for his face is of brasse)

Another English churchman, Thomas Fuller, used the imagery again in The Holy State and the Profane State, 1642:

His face is of brasse, which may be said either ever or never to blush.

The earliest printed example of ‘as bold as brass’ that I know of in print is in George Parker’s book Life’s Painter, 1789:

He died damn’d hard and as bold as brass. An expression commonly used among the vulgar after returning from an execution.

Brass has been used as the name of the metallic alloy since at least 1000AD. Why brass was chosen as a synonym for boldness and effrontery isn’t clear.

See other ‘as x as y similes‘.