The gelatine process consists in printing the picture on a sensitised film of gelatine. Now if this gelatine is soaked in water the parts representing the whites swell, and the darks, really the picture, remain as they were, as the light has rendered them insensible to water; from this swelled gelatine mould a cast in plaster of Paris can be taken, from this a wax mould is made, and finally an electrotype. The process is only used, I believe, by one firm; the results are good, but no better than the others.
Let us consider for a moment what are the advantages and disadvantages of mechanical reproduction. The first advantage is rapidity of production—a facsimile wood engraving may take weeks to produce, a mechanical engraving takes a day or so; this is not an artistic but a commercial gain. The wood engraving loses, the more intricate and complicated and close the details become; the mechanical or process engraving not infrequently gains.
The wood engraver may make mistakes in cutting the lines in the wood block, but if the lines are properly put down, the camera and the process engraver should not; and if they do, much less time is lost and labour wasted than with wood engravings.
Mechanical engraving is a much less costly method. These are not any of them very artistic reasons, but they count with publishers, and they count with you. But the great artistic advantage is that the artist may make his drawing of any size he wishes; it is not cut to pieces but preserved, and if it is properly drawn, as I have explained to you, it should produce in complicated work a more faithful result. In simple line work it is almost impossible to tell a wood engraving from a process block.
The drawbacks are that the line is sometimes too faithfully copied—that the engraving is shallow, and that the wood yields a richer, fatter effect than any metal, mechanical block.
These are artistic drawbacks, but they may all be overcome by the artist. The line, if good, cannot be too faithfully copied; the engraving, if shallow, can be made deeper, engraved anew by the wood engraver. The fat line so much prized was made with a brush, and, as I have said, brush work reproduces perfectly. And in the majority of cases the original wood or process blocks are never printed from, but casts of them called stereotypes or electrotypes are used; therefore the fat line of the wood is more or less the product of the imagination. I do not mean to say the original wood or metal block will not give a richer impression than any cast from it, but I do say it is only in the case of proofs that the original is used.
If a pencil or other drawing in line is to be reproduced, in which the varying colour of the pencil mark is to be retained, its greyness for example, or if the pen line is very delicate, or there are many single unsupported lines in the drawing, another method must be employed. A microscopically ruled glass screen, ruled with fine lines made with a diamond and filled in with ink, is placed in the camera in front of the glass plate on which the picture is to be photographed. There are various ways in which this is done, with the object of breaking up into line the tones which would otherwise print perfectly black, or, of supporting those weak lines which would print too heavily. This negative thus obtained is printed on to the zinc or copper plate, is then etched much as in the case of the simple line block. This process, usually called half-tone, was invented for reproducing wash, but is much used now for line, especially when the dots or line of the screen are cut away by the wood engraver in the whites. The photo engraver is now endeavouring so to shift or adjust his screen that the dots will come only where they are wanted to break up the solid black, and some most interesting results have been obtained. When I am describing the reproduction of wash drawings, I shall return to this subject.
Spaces of tint on line drawings can be and almost always are obtained by the use of what is known as shading mediums; that is, pieces of gelatine or copper with lines or dots engraved in them are filled with printer’s ink, and these lines or dots are transferred by the engraver to the parts of the picture on the zinc plate where they are wanted before the plate is etched. There are many ways in which the artist can get the same effect by inking bits of silk and pressing them on the drawing, by inking his thumb, or by drawing with a pencil or chalk or even pen over a rough book-cover, the only object is to get a bit of tone in a line drawing: in cheap work it is often very effective, in the best work it is usually out of place. All the artist need do is indicate the spot, or the outlines of the parts where the tint is wanted, by a blue pencil. If the engraver knows how the block is to be printed he will use the tint that will print best. They are all useful, but not very sympathetic.
Photo-Lithography and kindred methods are either of little importance or will be referred to under Lithography. Finally, if the lines are too black or too strong they can be cut away or thinned, or darks opened up by the engraver, just as on a wood block; or a little wheel in a handle called a roulette may be run over parts of the engraving which are too heavy—the teeth of the wheel break the lines into dots and lighten them.