In this way each side is treated alternately until the back is evenly rounded. The rounding of the fore-edge should be equal to one-third of a circle.

Books that have been hammered so much that they fall straight from the centre towards both sides are called "over rounded"; if, on the contrary, the book is round at the sides and almost straight in the middle the book is called "flat rounded." The latter occurs when the thread used in sewing has been too thin or held down too much (see page 37). Great care must be taken to avoid what is called springing a section--this is generally caused by a break in the glued back; but it is almost impossible to round a book perfectly if the sections are very thick or if it contains many pasted-in plates.

There are now very useful machines for rounding books, also hand machines. The work connected with these consists simply in turning the book a few times, pushing the back up to the rollers each time.

Fig. 39--Rounding machine.

When the book is properly rounded, it is "backed," that is, it is so placed between backing boards that they are away from the back just as much as is required for the groove, the width of the latter depending upon the thickness of the boards; a small thin volume gets thin boards and therefore a small groove; a thicker volume requires thick boards, and, of course, a deeper groove. The made groove should be a little deeper than the board set in it. The book and backing boards are placed in a wooden press, s.c.r.e.w.i.n.g up by hand and once more carefully adjusting. To do this, the press is first placed lengthwise on the table so that one end projects a little over the front edge of the table; the evenness of the rounding is then perfected--one hand at the back and the other at the front edge pushing and adjusting. The better and truer the book has been rounded before laying in the boards the less there will be to do when placed in the press. If the rounding is correct, the head and tail must be examined to see that they are exactly rectangular, for the book may have been knocked untrue, and the evenness of the grooves--which are easily disturbed--is also examined.

Backing and rounding is the most important work as far as regards the appearance of the book when finished; it must be done with the greatest exact.i.tude and requires much practice. Although it is hardly perceptible, yet the great difficulty lies in the book itself being so very easily shifted.

When the book is placed in the press without a fault it is screwed up as tightly as possible with the screw key, and through this the grooves already project over the edges of the backing boards; but a sharp groove can only be obtained by the help of the hammer.

The hammer, however, must not be used blindly on the back, but by lightly knocking, blow by blow, the first and last 4-6 sheets must be brought over the edges of the boards. This done, the whole of the back is well pasted, and after remaining thus a short time it is then rubbed with the point of the hammer along the sheets until all superfluous glue is soaked and sc.r.a.ped off. With a handful of paper cuttings the back is rubbed smooth and clean. The use of a toothed _cachir_ iron is strictly forbidden, but the round side of this tool may be used instead of the hammer.

Fig. 40--Backing machine for small shops.

For backing, we have also a useful machine--the backing machine. For small shops it is made for clamping only, and the making of the groove is done with the ordinary hammer. For large shops this machine has a roller going right across the back which forms the groove down each side.

Fig. 41--Backing machine for large shops.

Valuable books are either trimmed at the front and at once backed or they may be backed before tr.i.m.m.i.n.g. This is generally done with bulky books, as they are liable to throw out a section, and this danger is lessened by backing first. The work of backing remains the same. If the fore-edge has already been trimmed, care must be taken that the grooves do not suffer during tr.i.m.m.i.n.g after backing. One way of effecting this is to lay the book on a special cutting board with the edge up to the groove, or by making use of the arrangement on the clamp already described, and adjusting the groove of the book to the blocks fixed on the clamp.

Should the fore-edge not have been cut, the book must again be knocked straight after backing; to do this a strong cord is tied round the book about 1-1/2 cm. from the back, the book is then laid upon a firm bed, and the back again knocked straight; this work is called "tying up."

Fig. 42--Backed book arranged for tr.i.m.m.i.n.g.

It facilitates the work if the book is taken up and lightly held in the left hand whilst the right holds the hammer and knocks the round inwards until the book is once more square.

The squared book is now trimmed, and it is not until the tr.i.m.m.i.n.g is finished that the cord is loosened.

In pressing, several volumes of the same size can be done in the hand press at one and the same time.

CHAPTER IV.

MARBLING, GILDING, &C., THE EDGES AND HEADBANDING.

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 coa.r.s.er 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 pa.s.sable only when carefully and skilfully executed; as a rule they look coa.r.s.e 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, bis.m.u.th, 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.

Footnote 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.

The book must be pressed for pasting the edges, and the paste colour must not be laid on too thickly or it will spring off when dry.

Coloured as well as paste edges will take gold tooling and afford considerable scope to the skilful and thoughtful workman.

The finest way of finishing edges and the one allowing greatest variety of treatment is known as marbling; this is a special process.

Formerly regarded as a secret art, it is now an easily acquired branch of our work, thanks to the careful experiments and excellent demonstrations of the master bookbinder, Herr Joseph Halfer, of Buda Pesth.

The whole process of marbling depends upon the peculiarity possessed by colours of floating upon a sized surface when they are mixed with oxgall, and a colour containing more gall forcing off the one first applied. Besides, the colours may be drawn about with a pencil or stick without their mixing. If the smooth edges of a book are brought into contact with such a floating surface-colour they will take up the colours completely.

Ground and colour must each have certain fixed degrees of consistency, and the atmosphere both in and out of doors has also a great influence upon the work.

The prepared body, shortly known as "the body," is at present always composed of boiled Carrageen moss. To every litre[3] of water exactly 12 g. are added and the liquid is put in a saucepan, which is never used for any other purpose, and placed on the fire, great care being taken to catch it just at boiling point or it will all boil over. At the right moment take the saucepan from the fire and strain the contents through a hair sieve, what remains being thrown away as useless. The body may be used the next day, but for figured edges it is better after having been kept three days, and for veined marbling five days. The vessel containing the body must be kept covered so as to exclude all dust.

Footnote 3: Not quite a quart.

Gum tragacanth (known as "gum dragon") can also be used as a body, but Halfer's colours are not intended to be used with this.

A marbling trough to contain the body is used whilst working; it is made of zinc plate, is about 15 cm. in width, 50 cm. in length, and 3 cm. in depth, and has a sloping part.i.tion soldered near one end, and the colour not taken up is drawn into the division thus made.

Ill.u.s.tration: Marbling Trough

A bowl, about 6 cm. across the top, is kept for each colour, and also a hog's-hair brush and a birch-twig brush.

A small bundle of birch twigs is tied round with thread, leaving about 4 cm. of the twigs free, the thickness of the lowest part tied not exceeding 1 cm. The bristles of the brush are tied back so as to form loops and held awhile in boiling water so that they retain their shape after drying and untying. With a brush made up in this way, drops may be laid on anywhere.

For all drawn-out edges only bristle brushes are used, whilst for all other edges a brush is used only for laying on the first colour. For some edges a wide brush is used, so that the whole trough can be filled at one blow; a carpet brush with a short handle is most convenient to use.

A little stick for tracing the colours is also necessary--a butcher's skewer is as good as anything. Besides this, the colours are drawn by combs of various widths; these are easily made by glueing pins with their heads at fixed distances between two strips of mill-board: the result is a tool resembling a comb. All requisites can be conveniently kept in a little wooden box together with the colours. Nowadays only Halfer's ready-made colours are used.

Fig. 43--Marbling outfit.

Any one wishing to learn the process of marbling edges would be wise not to attempt all the styles at once, but should be content to learn one before proceeding to another. We will commence with "comb" marbling, also known as "feather" marbling.

When marbling is to be done, the colours must always be tested first. A little colour is shaken into each bowl and its brush placed with it, and one or two drops of prepared oxgall added to each colour so as to make the colour float on the surface.

One prepares one's own oxgall. An ox gall in the gallbladder is procured from a butcher, a gla.s.s funnel is placed in a bottle which has been weighed beforehand, and the bottom of the gall bladder is pierced so that the bladder empties its contents into the bottle. After finding the weight of the gall, add to the weight of the gall alone one-sixth and pour into it spirit of wine until the weight is equalized; shake thoroughly and strain the mixture, which will now be quite clear and ready for use.