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 red. They are most often half red and half blue, but some are 70% red and 30% blue. An editor-in-chief would use a blue colored pencil to make proofreading marks and final notes on manuscripts before sending it to be typeset and published. The pencils and their blue 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!

— Alice Corbin Henderson

Since the introduction of desktop publishing, editing is typically done on computer files and without literal blue pencils. They continue to be used in the Japanese newspaper industry and elementary schools in parts of Europe. A different type of non-photo blue pencil is used by some comics artists for different purposes.

Neither the exact date that blue pencils were introduced nor the details of how they became an editing standard are certain. Blue checking pencils were sold in the United States during the nineteenth century. Eberhard Faber offered a range of two-color pencils by 1873. Multinational manufacturer AW Faber sold wood and mechanical blue pencils in the late 1800s. By 1888, "blue pencil" was being used as a synonym for "edit" or "censor". During World War II, bi-color pencils were used to mark troop positions on maps.

Blue pencils became associated with editorial control and with censorship. Under the Estado Novo in Portugal the "blue pencil" became a metaphor as editors would use blue pencils to censor out portions of works rather than banning the entire text. In parts of Africa, the "blue pencil" became a metaphor for the censorship and banning of entire books.

In parts of Europe, blue pencils are used in elementary schools. In Hungary, children are taught the difference between uppercase and lowercase by writing the cases in different colors. In Germany, they are used to write separate syllables and numerical digits in alternating colors. In Italian classrooms, they are used to mark separate types of errors.

The blue pencils for schoolchildren are sold as "copying pencils" or "post pencils". In early twentieth-century Germany, blue pencils were used to mark postal routes. Checking pencils have been called "post pencils" as early as 1909 in Europe.