With three coats of a special paint, similar to that used in the offshore oil industry, painting of the bridge is due to be completed in four years. The paint has an estimated life-span of 25 years, although it is hoped it will last closer to 40 years.
But what Network Rail, the owners of the Forth Bridge, stands to gain in productivity, the English language could lose a cherished aphorism.
According to the Cambridge International Dictionary of Idioms, if "repairing or improving something is like painting the Forth Bridge, it takes such a long time that by the time you have finished doing it, you have to start again".
What might take its place? "Like Northern Rock paying back taxpayers," suggests one reader of the BBC News website.
Tell us your suggestions for a new "Forth Bridge" metaphor using the form at the bottom of this page. The following might supply some inspiration.