All work not turned-in which requires repeat blocking, and all such as requires blocking in more than one colour, is "pinned on." On the other hand, covers which are finished after being once blocked on back or side which require no second impression may be adjusted with the angle gauge or blocks. Many make use of both at the same time. Such covers then have been turned in all round when being worked, whilst "pinning on" requires that the covers should not have been turned in.

The practical bookbinder who has to deal with turned-in covers frequently gets over the difficulty by making two incisions about 2 cm.

apart with the knife upon the turned-in edge at the place where it should be pinned on, and opening out the material at the incisions, thus making a loose margin for pinning on.

For pinning on covers as well as backs, a template is cut from wrappers or thin board, which is adjusted on the cover and the register holes made with an awl. When pinning-on has to be done for blocking which has to be repeated very many times, the register points are strengthened behind with stiff paper to prevent them from breaking or tearing away and thus becoming inaccurate.

Fig. 65--Appliances used in blocking backs.

To enable the most various widths of backs to be quickly inserted and to supply a subst.i.tute for the thick layers of cardboard packing which make a fine impression impossible, a special contrivance with metal pads has been made. This is shown in the sketch herewith.

Mention has already been made of the table (or matrix). This is a bed of stout boards which is intended to serve the double purpose of saving the blocks when blocking thin articles (backs of covers, &c.) and also for strengthening and equalising the resistance from below when working on heavier articles. Faults arising during working, such as insufficient adhesion of the gold (and an increased pressure) may be set right by pasting on pieces of paper to the matrix or table.

The matrices consist of strong but thin material; the best is wrappers or the thinnest board. After use they are kept for subsequent repet.i.tions of the same or for other work.

The lettering must always be set up fresh for each job, whilst the ornamental pieces may be arranged on the tables or matrices at hand after the existing original impression.

Setting the type is a special art and calls for considerable taste and skill; the letters very easily slip out of the type-holder, especially where very small type is used, unless special precautions are taken to prevent this. Here we will pa.s.s over the most important point in the arrangement of the types and refer to the paragraph dealing with "Lettering" under "Hand-tooling"; what holds good there always holds good here.

Lettering is always set upon special pieces of board and afterwards encased in a type-holder, as it demands much more attention and subsequent correction. These boards should likewise be wrappers of the same thickness as those used at the same time for the ornaments. For fixing, cobblers' wax is likewise used. The favourite method frequently adopted of using glue coated with paste is not to be recommended, because the letters do not admit of proper setting upon this gelatinous ma.s.s. Not only do the lines of letters require to be kept right by means of a strip of metal or metal line, they must be carefully adjusted after taking a light impression, especially when using a very small type. The first pull must be under so light a pressure that on a soft paper everything is distinctly visible. The lines are arranged from this proof, whilst each single letter is carefully checked. Where letters do not show up properly they must be backed up with paper of suitable thickness on the board until all unevenness disappears. The lighter the pressure applied the easier it will be to make corrections. Letters heavily pressed at the outset can seldom be properly rectified afterwards.

In large editions it does happen, in spite of all precautions, that single letters work loose and fall out; this may damage parts of the plate as well as valuable covers, and one therefore tries to guard against it. Some take narrow strips of cloth and paste one round each line of type, others pour liquid glue between the lines which, when thoroughly dry and hard, is a very sure means of preventing the falling out of any piece of type.

When everything is in order, the type is likewise inserted; various parts of the back of the board are well waxed and the table is then pushed in and the press closed tight. It remains closed until all parts are thoroughly dry, for it is only then that we may feel a.s.sured that no parts can fall out. The drying may be hastened by opening the press about a quarter of an hour later and drawing out the plate, likewise the table, and now allowing plate and table to dry by exposure. If any parts of the plate should lift, wax must again be applied and once more pressed.

When the plates and press are got into working order, and the backs or covers have received their register marks by means of the template, the blocking may be commenced. The table is drawn out, a piece of work pushed in to the register, and the press closed. It is necessary that the press should have been previously regulated to the thickness of the article being blocked, and to begin with a light pressure at first, as heavier pressure can be applied afterwards if required. Cloth requires sharper pressure than leather. Large heavy covers are always blocked with the press quite closed, whilst small things like single t.i.tles, hat linings, ties, &c., are finished with only a short pull of the lever.

The correct regulation of the pressure rests with the worker.

We distinguish between blocking in blind, gold, colour, and relief.

Blocking in blind, both on leather and cloth, should not be attempted upon articles which have become very dry. A good plan is to store them in a cellar the night before and to bring out only as many as can be finished in the next half-hour's work. Blocking in blind can only be done on matt or grained material, as its effect is nil upon a smooth polished surface.

The finish can be considerably heightened in special cases by going over the impression with a brush and white of egg after the first blocking and then again pressing under less heat. Calf leather, and undressed calf in particular, receives its splendid brown colour by being previously damped with boiled or distilled water to which a little spirit has been added. The impression on a damped ground is first made somewhat warmer and afterwards repeated when the press has cooled a little, occasionally wiping the blocks with a waxed cloth. The impression must in all cases be even in colour and have a high finish; if this is not so, the lighter places must be once more damped with a small brush and again impressed.

Articles to be blocked in gold must be prepared with some substance to which the gold will adhere. The finisher uses a fluid or dry adhesive according to the material he is working upon. Of liquid sizes, diluted white of egg or, in some cases, dissolved gelatine or blood serum is used almost exclusively. These liquids, which are applied with a sponge or, for fine work, with a brush, are called the "ground" or "sizing." Of dry adhesives, we know only the gilding powder, which consists of resin with now and then an addition of dried white of egg. The other powders used by the finisher are rice flour or potato flour; these are not used as adhesives but to prevent the gold sticking at places where it is not wanted.

Leather and cloth are sized with white of egg; silk and other woven materials are finished without special sizing, and also surfaced papers and cardboard goods, as they are treated with finishers' powder, a wet preparation being unsuitable.

Size for blocking is thinner than for hand finishing, and when it has to be washed over the whole of a cloth cover it is still further diluted.

Glair for brushing over an impression consists of one part white of egg and one part vinegar; to every 1/2 litre 1 g. of powdered borax is added, the whole beaten to a froth and filtered. For coating-over, take one part white of egg, two parts water, and to every 1/2 litre add 10 drops of glycerine and 1 g. borax. If a larger quant.i.ty of glair is required for coating over, it may be thinned with water or vinegar; but size made with vinegar must not be applied to fancy coloured cloths.

Gilding powder may be yellow or white, the latter kind is rougher and is suitable for silk stuffs and also where blocking has to be done over colour on cloth. Yellow powder is softer and is apt to clog the finer cut tools; it is more suitable for the preparation of paper _de luxe_, for blocking surface and chromo papers, and for photo cases.

Gilding powder is sprinkled by means of a box which has a double layer of fine gauze instead of a bottom. By tapping upon the box a fine shower of powder is dusted on to the surface to be gilded.

Glair is made in the workshop; the powder is bought ready prepared--to make it would take too much time.

For blocking in alloyed metals, gelatine size is used, as it is a powerful adhesive. A tablet of gelatine is soaked in 1/4 litre of water overnight and next morning is dissolved in the bath. Gelatine is used to cover the whole surfaces and is laid on when lukewarm. Blood serum serves the same purpose. Ox blood is allowed to coagulate, and the hardened ma.s.s thus produced is placed over a cloth strainer, or hair sieve, and the liquid alb.u.men allowed to drain from it; the process is hastened by cutting the caked blood into small pieces. Only the clear liquid which is strained off is to be used--a pinch of borax will make it keep longer.

For finishing bindings, real gold-leaf--orange tint--is used almost exclusively, the cheaper green gold being used only for sample cases and school books. Alloyed metal and aluminium (this is now commonly used instead of the quickly oxydizing silver) are used almost solely in the manufacture of papers _de luxe_ and for placards.

Pure gold-leaf is always laid on the sized cover after the surface to be blocked has been lightly gone over with a ball of oiled cotton wool, or a slightly greased rag. This must never be done to such a degree as to cause grease spots. Calf must not be thus treated with grease, but if the gold is not likely to stick at certain places, the first impression may be picked out with a brush slightly oiled so as to make the leaf adhere. Dark polished calf will, however, stand a little oil.

Fine leathers are first stamped and the impression is gone over with a brush, then the gold is laid on and again impressed. The gold is lifted from the cushion with a gilder's tip or a pad of cotton wool and transferred to the cover. The gilder's tips consist of square pieces of cardboard a little smaller than the piece of gold to be used, to the under side of which is pasted a piece of cloth. A handle of cardboard or a b.u.t.ton is pasted on top for convenience of holding.

Draw this tip lightly over the hair, press it on the gold, which will lightly adhere to it, and then transfer the gold to the surface to be stamped, where it is pressed down with cotton wool, which should be surgical wool, as that kind is free from knots. Many prefer a tuft of cotton wool rolled into a handy size, this is likewise drawn over the hair, and the rest done as before.

When gilding powder is used, the gold must not be laid on with the pad.

The gold must be placed on the powder by hand only, a task calling for considerable adroitness. The gold is taken up with the gold-knife, aided by a moistened finger-tip taking a corner, pa.s.sed over the surface with the knife, brought to the required position with the hanging corner, and now the knife is taken away flat sideways. The gold must lie quite even on the powdered surface. Any subsequent shifting of the gold is entirely out of the question, because the layer of powder would be disturbed and might not hold in places.

To know exactly what degree of heat should be applied requires special study, and the pity is that fixed rules cannot be given--one day a black morocco goat-skin may stand a great heat, whilst on another day the same heat applied to similar stuff might burn it up. Cloth is always the same, calf leather papers, skytogen, &c., are much more difficult. On the whole, the following rules may be observed:--

Cloth white of egg (or glair) medium heat Sheep-skin " slight heat Goat-skin " medium heat Morocco " medium heat Silk white gilding powder short hot pressure Surface papers and cardboards yellow " " short medium pressure Calf glair hot (light leathers somewhat less heat) Varnished paper little heat

The latter contains sufficient adhesive matter in the colour without using any other size, even for alloyed gold, but the covers must, however, be slightly moist. For this purpose they are left overnight in a damp cellar or placed between slightly damped boards.

We have already spoken of the matrix. Where silk or other thin woven materials are to be blocked, a firm hard board must be laid on the table and frequently changed, otherwise the impression will be defective. For ribbons for wreaths, &c., a suitable piece of paper which had been damped some time before should be laid underneath.

Although relief blocking upon bindings seems to be out of favour, there are numerous styles of imitation relief practised nowadays, especially in imitation of cut leather or wrought metal. This work necessitates the matrix or table being prepared with great care, as it must be the counterpart of the plate. For this purpose an impression is first made upon a stout cardboard, which is fixed firmly enough on the bed to prevent its shifting, the block being affixed to the platen. Upon this first cardboard are laid the raised parts according to the height required, likewise cut out of stout cardboard, continuing to place a layer upon the other until a true negative of the block is obtained.

Small and slightly raised ornamentation is not specially underlaid, using instead a piece of stout board well smeared with cobblers' wax, which, after standing awhile under the plate in the closed press, will make a very exact and firm base. Matrices made up of several layers of cardboard pasted on top of each other are also, when finished, covered with a piece of pasted packing paper and then pressed. This leaf prevents single pieces from working loose and sticking to the block.

For relief stamping, leather or cloth is stretched upon thin wrappers.

The guide points must be made a little further apart on account of the material shrinking slightly under relief stamping.

Colour blocking, which has gained such unexpected popularity, gives the finisher no little trouble. As blind blocking is done by the press, so also may colour blocking be done if the blocks are coloured with the brilliant colours specially prepared for printing. A colour roller, made by moulding English roller composition on a wooden pin, is used for colouring the blocks. The worker himself may cast these rollers in a well-greased mould. The roller composition is dissolved in water, and after being poured into the mould is allowed to stand a few hours to cool. The colour blocker keeps about three rollers ready, of which one is used for light colours, another for middle tones, and the third solely for black. The rollers are either fixed in a fork with two handles or an axle goes through the wooden pin which is bound in leather at each end wherein the axle revolves in the hollow of the hand.

Fig. 66--Colour roller.

The rollers spread the colour upon a stone of suitable size. The colour should be laid on the rollers--not on the stone--not too thickly, and then evenly distributed on the stone by bringing the roller over it backwards and forwards. Both stone and roller must always be cleaned after use; perfect cleanliness must be carefully observed throughout.

The stone is cleaned with petroleum, the remaining colour is removed from the roller by pa.s.sing it several times over a sheet of gla.s.s, rubbing it down with petroleum before again using it so as to remove any particle of dust adhering.

In order that the colours may appear as bright as possible, a little varnish is added to them, which in every case must be of a kind to suit the particular colour. Dammar varnish is suitable for light colours, and for darker colours amber varnish. Where great brilliancy is required, Venetian turpentine is added; but this lengthens the time required for drying if a little too much is added.

In every case, however, a little siccative must be added to every colour; a few drops materially quicken the drying.

Colour blocking can only be done when the blocks have been secured to the plate, as this must be opened each time it is coloured.

The simplest colour-printing is where one colour appears between the impression in gold, and in this case it is generally done by first making the impression in gold and then in colour.

In more complex work several colours are to be used; at the present time the work is frequently produced requiring colours side by side and superimposed, together with gold, bronze, and aluminium.

The process is in each case as follows: From the block supplied by the engraver an impression is made which forms a matrix. It is best to select a piece of board exactly the size of the covers to be printed and at the two places to be taken by the guide points pieces of vellum are firmly pasted, being already pierced for the guide points, these vellum additions being further secured by pasting over them a strip of paper or cloth. For every block to be used a similar board with its vellum additions is prepared. Upon the ground of this first matrix the other auxiliary matrices are likewise first impressed with the block--all of them black, of course, so that it would be possible at any time to fit in the blocks.

Every new block for colour printing is pressed into the ground of the auxiliary matrix belonging to it; also for the so-called first-impression block.

It must be understood that colour printing can be done well only upon a perfectly even and smooth surface, therefore it is wise with first-impression blocks, as well as larger colour plates, to repeat the impression, only slightly warm after having given a very hot impression the first time.

Surface papers are an exception as they generally stand very little heat.

It helps here either to let the newly made covers get half dry or, better, to let them lie longer in a damp room.