Edwin Bale

“ Whichever metal may be used, a sheet of it, most carefully planished, is sensitized with a coating of gelatin or fish-glue and bichromate of potash, dried and exposed under the screen negative to the action of light, as in the ordinary method of photographic printing. The action of the light hardens the gelatin film, the portion not so hardened being soluble by water. The plate with the gelatin picture in lines and dots is exposed to heat and the image is burnt in on the surface of the metal like an enamel, which enables the photographic picture to resist the subsequent etching. ”

“ Years were devoted to the production of one steel- or copperplate, while wood engravers who were artists could only work on a block when in the mood; and for that mood the publisher had to wait, and he grew impatient and was willing to accept rapid interpretation of originals by men who could produce them under other than artistic conditions. ”

“ This three-colour process has been a rather long time in establishing itself and nothing has so tended to retard it as bad printing. Good blocks have been obtainable, but in the hands of ordinary printers they have yielded but indifferent results. It is hardly to be expected that the untrained eye of the ordinary printer should be successful where the work requires the cultivated judgment of an artist. There is one other necessity for success in all tone relief work, and that is the use of the right quality of paper and ink. ”

“ On passing a current of electricity through the liquid to the mould, the copper at once begins to deposit itself in metallic form over the face of the wax mould, and in a short time the deposit becomes thick enough, either by itself or when backed up with other metal, to be used as a block in the place of the original. The very fine nature of process blocks, and the necessity of obtaining perfect impressions from them, has led to the introduction of gutta-percha instead of wax as the medium for making a mould. ”

“ The old soft blanket kept the cylinder or the flat press in contact with the type, in spite of the weak construction of much printing machinery. The new method of work made no allowance for such construction; and the new machinery, to meet the new conditions, had to be very perfect in manufacture. About the old machines there was a lack of solidity, which allowed vibration. Modern work demands absolute rigidity in the machine; and a chief characteristic of the best modern printing machinery is strength and solidity, admitting of precision of impression. ”

“ It is the printing that makes its use expensive, rather than the making of the plates; and as each plate must be printed separately and on special paper, it cannot be employed with type, like relief blocks.
There is much uncertainty about the production of plates by the photogravure method; and although great improvements have been made in the process, it is often necessary to produce several plates before a satisfactory one is obtained. In all these reproductive processes the more artistic the workman the better the result ”

“ It is not possible to lay down a rule for the amount of reduction to be made when photographing for the reproduction; the liner the drawing the less should be the reduction made; but experience is the only guide. ”

“ Collotype or phototype is a process in which the film of isinglass, gelatin or gum, treated with bichromate of potash with the addition of alum or some other hardening substance, becomes an actual printing surface inked with an ordinary roller and printed by an ordinary machine. ”

“ Relief Processes.—An engraving in relief is one in which the printing surface stands up above the surrounding ground. The history of the development of relief processes is really the history of photography (q.v.) ; for whilst attempts were made to obtain results without the aid of photography, by drawing upon plates with prepared chalk or ink, “rolling them up” with printer's ink and etching away the ground with acid, as in the case of zincography, the real progress of all process has been upon the lines of photography ”

“ This three-colour relief process has made great advances in recent years. The first great practical difficulty which had to be overcome was to produce three screen blocks which could be printed one over the other. Were the screens of each block used at the same angle, the lines and dots would print on the top of one another; but a great deal of the colour result depends upon a considerable proportion of each colour being on the white paper. Artists know well that much purer and more brilliant results are produced by placing touches of colour side by side than one over another ”

“ The lines of an original may be of any variety of thickness. It is necessary, therefore, for the draughtsman to see that he works with a good black ink, or ink that will tell as black when it is exposed to the photographic plate. Inks of a warm tone—that is, inclining to red or orange—yield better results than cold inks which incline to blue.
Most prepared liquid inks have a tendency to lose their blackness by exposure to the atmosphere on the removal of the cork from the bottle. The ideal ink is one freshly ground from a dry cake of colour when beginning work. ”

“ The means at his disposal were lines and dots, which, varying in their thickness and proximity, expressed dark or light passages in the scheme of light and shade of the original. It will readily be understood how such interpretations would vary. An engraver with fine art instincts would produce a result as distinct in character as an engraving as was the original as a painting or drawing, and engravings were sought after as works of art, and treasured for their artistic qualities. ”

“ The usual methods of lithography are then followed, the stone is treated with a preparation of acid and gum, kept moist and printed from in the ordinary lithographic method. Lithography of all kinds can only deal with lines or solid blocks. Tints present difficulties which are best dealt with by other methods of reproduction, but attempts have been made to obtain tints lithographically by breaking up the solid surfaces of the gelatin print with a grain before rolling it with ink and transferring it to the stone. ”

“ Steel-facing is resorted to where long numbers have to be printed from photogravure plates. The finest film of steel is deposited by Steel-facing. an electric battery over the whole face of the plate, which it hardens and protects. This steel face in time begins to wear, through the constant pressure and rubbing incidental to the process of printing, and the copper begins to show through it. As soon as this happens the plate is placed in an acid bath, in which the steel film disappears. ”

“ It is a secret Rembrandt Intaglio Process. process; but the secret lies more in the press by which the plates are printed than in the plates themselves, which are intaglio plates made with a very fine screen and bent to a cylinder. The attempt to print photogravure plates by machinery was given up because the plates were so shallow they would not stand the wear and tear, and their life was too short and the results too indifferent; but the use of the grain screen renders possible stronger, deeper plates, that will stand harder wear. ”

“ As soon as the acid has eaten its way downwards past the protecting surface film, it will attack the sides of the upstanding dots as well as the ground that supports them, with the result that they become weakened and rendered liable to break off in the process of printing, as well as to make the obtaining of electrotypes from the blocks a matter of extreme difficulty, the underbitten points breaking or tearing away in the mould. ”

“ It is true that the addition of hand engraving can be resorted to in the case of the process block, and lights and other varieties of tone and form introduced, but this can only be done on blocks of very fine texture, and the cost of reproduction is greatly increased by the introduction of such handwork by the engraver. ”

“ If, for example, the filter for blue records the full strength of blue with the full strength of the colour of the negative, while giving slight or no record at all of the red and yellow, it is practically a true filter. It is possible to treat the negatives themselves so as to render them more sensitive to the special colour they are intended to record. Indeed Dr Albert, of Munich, has produced a collodion emulsion which is so sensitized that the various colour sensations are directly obtained without the interposition of a colour filter. ”

“ It is only possible to approximate to the printing of a flat or graduated tone by producing a broken or granulated surface which shall present a series of lines or dots that, when inked and impressed upon paper, shall by the variations of proximity and size give the impression of an unbroken tone. ”

“ It is melted and poured in a liquid state upon the block, and when cold can be removed without the risk attending the use of wax, which is apt to give way in the course of the separation of the block from the mould. Gutta-percha is much more tenacious, and being somewhat flexible, does not break and tear, as wax is liable to do. The whole process requires the greatest care in its manipulation. ”

“ There must be the most perfect register of the three subjects, otherwise a blurred effect results; there must be constant watchfulness to see that there is no excess of ink of any one colour, or the whole scheme of colour will be destroyed. ”

“ Planographic processes are such as are printed from a flat surface neither raised above the surrounding ground like a wood engraving or type letter, nor sunk below the ground like an etching or steel engraving. ”

“ Indian ink is good if well ground and kept sufficiently thick to assure the necessary blackness. It has the advantage of not washing up when colour in washes is passed over it, but it must be used freshly ground. ”

“ Besides the pen a brush brought to a fine point is much preferred by some artists, as it yields a line less monotonous than that given by a pen, though the brush cannot be used so freely. The paper used should be smooth and as white as possible. ”

“ Paper makers are, however, supplying a dull surfaced highly calendered rag paper which is very good for artistic and scientific illustrations and obviates both the glossy surface and the supposed lack of permanency of chromo paper. ”

“ To produce a half-tone block from a picture, a black and white drawing in tone, or a photograph, a negative is exposed in the camera in the usual way, with this screen quite close to it but not in contact ”

“ There is little doubt that the machine used is some form of the machine used to print wall-papers, in which there is a central cylinder engraved with the design, inked by rollers with which it comes in contact. ”