Blue pencil (editing)

A blue pencil, also known as a checking pencil, is a two-color pencil traditionally used by an editor to correct a written copy. The blue end is typically Prussian blue, and the red end is typically a warm vermilion. They are most often half red and half blue, but some are 70% red and 30% blue. An would use a blue colored pencil to make proofreading marks and final notes on a manuscript before sending it to be typeset and published.

The blue pencil, and its colored marks representing corrections and excisions, became associated with the editing process and editorial oversight.

Of course it takes skill to be a poet! But an editor? A pair of shears, a blue pencil, and a paste-pot!

Since the introduction of desktop publishing, editing is typically done on computer files, without literal blue pencils. They continue to be used in elementary schools in parts of Europe, where they are known as "post pencils", and in the Japanese newspaper industry. A different type of pencil, utilizing non-photo blue (like cyan), is used by some comics artists.