The edges of a book are nearly always finished off in some way or another, as the plain white edges would quickly become soiled. As a matter of fact, the binder always uses a covering of gold or colour for this purpose, and care should be taken that this way of treating the edges is decorative and not the reverse.
In small binderies the edge is most usually sprinkled. A small brush with a handle (such as is used for blacking shoes) is dipped into a very thin coloured liquid and rubbed over a fine sieve which is fixed in a frame. The sieve is kept at sufficient distance from the edges of the book to allow the little drops of colour to fall like a fine rain. For this work the book is screwed up in the press (which is laid flat) by means of the press-jack. As a sprinkling colour, nut-wood stain thinned with water is used, or indigo, carmine, Prussian blue, mahogany brown, green cinnabar, all well diluted with water, with the addition of a little paste and borax or a few drops of dilute carbolic to prevent the paste turning sour; aniline dyes have a common appearance. The sprinkle must fall very finely upon the edges, therefore the first large drops should be taken out of the brush by giving it a few preliminary rubs over the sieve.
A few variations are made in sprinkled edges by scattering damp sawdust, sand, or bran on the edges before sprinkling, thus producing a coarser kind of sprinkling. Similarly rice, barley, even starch or drops of wax are used. All these edges are out of date and in really good workshops are every day falling more and more into disuse, preference being given to marbling upon a sized ground.
For the production of even marbling an edge-marbling roller has recently been brought out.
Rubber rollers—one or two—together with the automatic colouring rollers bearing aniline dyes mixed with glycerine, are made up into a handy contrivance by means of which smooth coloured edges can be rolled over. These edges are passable only when carefully and skilfully executed; as a rule they look coarse and common and are taken up only by badly equipped shops. Marbling rollers can be used for comb marbling as well as for small veined marbling.
We may say that the coloured edge is the oldest style.
Earth colours which cover well—cinnabar[2] (red or green), carmine, chrome yellow, graphite, bismuth, and also other colours that cover well, indigo, carmine, and Prussian blue—are ground to a fine powder and thoroughly mixed with water and a little paste or gelatine so that the edges may be evenly covered.
[2] Cinnabar if not red must be a preparation with other colour.—Trans.
Only printed books are put in the press, and in this case they must first be rubbed down with alum water. After about five minutes the colour may be laid on. Hog's-hair brushes are used for this. Recently, eosin has been used to colour red and picric acid for yellow, both well diluted with water.
The paste edge is a variety of the coloured edge; it is produced by loading paste with a very strong colour so that it covers well when laid on. With the blunt point of a stick, a bluntly pointed cork, or even the finger-tip, figures may be traced in the colour when laid on, and then the figures may be brought out better by going over the lines with a pointed stick. The work demands a skilled draughtsman if a good effect or something more than the very simplest design is desired.