run marbling

The process of decorating a covering material such as paper or animal skins in which a liquid has been dropped onto and allowed to run over its surface to leave irregular, flowing traces. The effect can be achieved with coloured stains, or by chemical means, or by a combination of both. The covering material could be so decorated either before or after it was put onto the book, but skin materials were most often decorated on the book (leaving the spine, board edges and turn-ins undecorated), whilst papers were more often decorated in the sheet, before they were put onto the book.