Deckle_edge
Paper with a feathered edge is described as having a deckle edge, in contrast to a cut edge. Before the 19th century, the deckle edge was unavoidable, a natural artifact of the papermaking process in which sheets of paper were made individually on a deckle, a wooden frame.[1] Today, machine-made paper may artificially have its edges produced with deckle edges.[2]: 456, 458
The deckle could not make a perfect seal against the screen at the edges and the paper slurry would seep under, creating a rough edge to the paper. The deckle edge could be trimmed off, but this extra step added to the cost of the book. Beginning in the early 1800s with the invention of the Fourdrinier machine, paper was produced in long rolls and the deckle became mostly obsolete. Although there was some rough edging on the ends of the rolls, it was cut off, and the individual sheets cut out from the roll would have no deckle edge in any case.[1]