blade

In more detail

Nothing comes off a press at its final size. A press prints a large sheet, several pages at a time, and the finished page is cut out of it afterwards. The blade is what does the cutting: a long straight knife, brought down on a whole stack of sheets at once.

It lands within a fraction of a millimetre of the line, and a fraction is enough to see. The paper breathes with the weather, a stack of five hundred sheets settles as it is squeezed, and the knife itself pulls very slightly as it goes down.

What it does on a real document

Two things on a press file exist for it. The colour is carried past the line so that whatever the blade takes, it takes ink. And short marks are printed outside the page, in the part that is thrown away, for the operator to line the knife up on.

The file states the line itself as well, on every page, as a rectangle a reader never sees. It is the difference between a job that goes straight through and a telephone call asking where the page really ends.

Where it comes from, and why

Cutting after printing is as old as printing on a large sheet, which is nearly as old as printing. Books were long sold with the pages still joined at the edge, for the buyer to open with a knife at home. The machine took that job over in the nineteenth century, and the geometry has not changed since.

See it on a finished document

A sheet as it goes to the press A sheet prepared for the printing works The rules behind this word, and the texts they are read from