Marbling, as it is known to bookbinders, is a method of making patterned paper by transferring color from the surface of a liquid to paper. These papers are then used for the endpapers, to hide the lumps and bumps caused by leather turn-ins and cords, or to cover the sides of books where patterned papers don’t show marks of wear so easily as plain papers.
The traditional manner of marbling paper is often called “Turkish” marbling or Ebru because it originated in the old Ottoman empire of the 15th century. Water-based inks containing ox gall (bile) as a dispersant are floated on the surface of water thickened with gum tragacanth or carrageenan moss (actually a seaweed). The colors are then drawn into patterns by means of sticks or combs, specially-prepared paper is laid gently on the surface, left for a few seconds, and just as gently removed, rinsed (to wash off dirty size or excess color), and hung to dry. Papers used should be fairly hard-surfaced and treated with alum as a mordant to take the pigment and to improve colour tone and colour fastness.
Another traditional form of decorating paper is Suminagashi, a Japanese method which apparently dates back to the 12th century, and which differs from the Turkish method in that the water is unthickened and the colors actually dye the paper (Japanese rice papers are usually softer and more absorbent), whereas in Ebru, the color pigments become attached to the paper surface.
Another, newer, technique for marbling paper is called “Swedish” and uses oil-based paint on unthickened water, the paint being thinned and dispersed by means of a solvent such as turpentine. Less preparation is needed for this technique, but control over patterns is limited and the papers take longer to dry. The paper does not have to be treated, nor need it be rinsed.
Finally, a very simple method of decorating paper for bookbinding is paste marbling, which is reminiscent of finger painting. Colored paste, made from flour and water (1:4) or other cold water paste and colored with watercolor or tempera paint, is spread onto paper and patterns are drawn with fingers, sticks, combs, or anything else at hand. While the end result is often less vibrant than traditional marbling methods, some very handsome and intricate designs have been created.