Georg Fritz

“ The undesirable half-tone must, however, always be broken up in some way into the requisite points or lines, as it is one of the characteristics of lithography that it is only possible to print from distinct figures on the stone. Lithography and letterpress printing produce impressions of sharply-defined lines or points, each of which must form a distinct whole. Any tone which is lighter or not absolutely black must be formed by lines or points standing in close proximity to one another. ”

“ It is indeed obvious that a discovery so important and useful to one of the principal departments of the graphic arts as lithography is, and which may be called even more essentially capable of variation and multiplication, and perhaps in its way also more artistic, should call forth an earnest movement on behalf of the technical experts, principally with the endeavour for simpler forms and extension of its powers of work. ”

“ Eder and Vogel, and these I may therefore omit so far as nothing novel is to be observed.
We distinguish now between daylight and artificial light studios; further, those in which a camera is used for making the negative and those in which a dark-room itself is the camera. The first will, of course, be used where other things besides reproductions have to be made; the arrangement without a camera presents many advantages for reproduction work only. ”

“ If the film of asphalt be thin and the negative clear it may be printed to 18 or 20 degrees in Vogel’s photometer. This kind of printing always requires some experience, as various factors, such as the thickness of the asphalt film, the density of the negative, also the fineness of the drawing, have to be taken into account. It will be understood that the asphalt film must always be coated as evenly as possible.
If it is printed too long the stone will not develop at all, or only in parts; if it is printed too little the drawing wholly or partially dissolves. ”

“ With the removal of the lineature from the sensitive plate, on the other hand, the ratio of tones for the whole image, as well as for the details, is displaced. In the first place we shall obtain a picture which contains more contrasts of black and white. The light tones become considerably lighter by the reduction of the shadows. The dark parts, on the other hand, attain full vigour. In the first place, therefore, the original has to be considered as regards the distance of the lineature from the sensitive plate. ”

“ It may be generally said, however, particularly as regards pen and ink drawings on smooth paper, that they should never be smaller, only very rarely of the same size; they should be drawn one-third or one-half larger generally. The artist can execute fine details more easily and precisely on a large drawing than on a small one.
The enlarged reproduction gives any faults or mistakes which may happen to be in the drawing in proportionately larger size quite independent of the fact that an enlarged reproduction is always somewhat rough and ordinary. ”

“ Over-printing is disadvantageous, as the lines and points become broader, the prints develop badly, the tint adheres firmly to the ground, and the details in the deepest shadows are lost.
The inking and developing can be done by any of the known processes which is thought desirable. The chief thing is that too much ink must not be used in the first inking up; any intensification required may be effected with a second coating. This is, especially for fine drawings and autotypes, very important, whilst for coarser work also once inking is sufficient. ”

“ If it is kept in mind that with too great reduction the gradations of tone of the print will be destroyed, and that in the same degree the difficulties of printing will be increased, care should be taken that reduction is not carried too far. When it is further considered that in a reproduction with 2,000 to 3,000 points to the square centimetre the individual points disappear to the unaided eye, and the different thick layers of points appear as closed tones, the limit of reduction will soon be found. ”

“ In this process there comes, however, to our aid a very important physical law, namely, the diffraction of light. A ray of light passing through a round hole or a slit and falling on to a black surface is represented not the same size as the slit, but more or less broadened the more the receiving surface is moved away, and in the middle the brightest light will be, and this gradually fades off into shadow towards the margin. ”

“ The material with which the print or drawing has been prepared; very fatty developing inks and asphalt stand well even with strong etching, whereas with lean or hard inks only a weak etching should be used.
An etching solution which is at the limit of strength, but still suitable for a hard stone or a very coarse drawing, would irretrievably ruin a very fine drawing on a soft stone.
Commercial acids differ considerably in strength, and it is, therefore, better to use a hydrometer than a measure. It is also always more satisfactory not to use the acid by itself, but in conjunction with gum. ”

“ When a stone or plate is coated with asphalt solution and exposed under a negative, and then washed with turpentine, the exposed parts remain insoluble, and in this way photo-lithographs can be prepared. The asphalt here takes the place of the fatty ink, and is, after printing, so firm and hard that without any rolling or inking up it can be etched with a weak, gummy, etching solution, which gives a cleaner, sharper drawing than the other processes. ”

“ The ink can be obtained in a liquid form and the two others in solid state. All three materials consist principally of soap, tallow, wax, resin, and soot. Soap and tallow give the necessary grease, wax and resin give hardness and consistency, and soot the colour. The proportion of grease in the drawing materials must be so great that even the finest lines or points of a drawing can be well transferred to the stone, so that they may not be attacked by the proper etching solution, and do not break away from the stone by continuous printing. ”

“ The development may be so performed that by the longer or shorter use of strong solvents, Hungarian or Russian turpentine, more or less of the asphalt will be dissolved. Thus if a slight error is made in printing it can be made good in developing. As a rule, the stones for bright colours, which consist of many tones, are not developed so long as those for the stronger colours. The actual stones for the deep colours are very strongly developed, so that almost all the delicate parts of the picture disappear, and only the dense strong parts remain on the stone. ”

“ Reproduction photography has to reckon on this disadvantage, for with a side illumination the raised up lines cast shadows, and a correct negative does not follow.
By the third method, lithography, of which we have already spoken, the impression lies generally flat on the paper like a drawing, if a very strong deep etching was not used, in which case it is also slightly raised. In printing from the graver or from stone etching a faint relief is generally noticeable, which is never so high as with copperplate printing, and which is no important obstacle to making a photographic negative. ”

“ This examination of the picture must be done in a dark room, and only one side of the printing frame should be opened, so that the print does not shift. If it is over-printed, the picture develops badly, the lines become broader, the details disappear in the deep shadows, and the ink adheres to the unexposed parts. If, on the contrary, it is under-printed, the ink does not adhere well to the exposed places, and washes off in developing from the fine parts. Practice, as with all manipulations, is necessary, and therefore one must not be disheartened by the first failure. ”

“ Whilst the light reflected from the brightest parts of the drawing acts with full intensity, and is diffracted over the figures standing in its path and makes the same smaller, and cuts off the sharp corners and gives more covered surfaces to the negative, as it decreases according to the more or less deep shadows of the drawing, and can only act now with less intensity through the open places of the screen, the result is that the points become larger, till finally in the deepest parts it is quite inactive, and the shadows begin to block. ”

“ The autographic ink is, as a rule, used for drawing or writing on paper, and the result is then transferred to the stone. Instead of this, any litho tusch can be used, but for some work the autographic ink is more advantageous. This ink must be thin, run easily, but not patchily, from the pen, and must keep for a long time equal in quality and action. It is very advantageous that specially-prepared paper is not required, since this always makes the work more difficult; firm, hard writing-paper is quite good enough for this work. ”

“ The very sensitive kinds of asphalt of Husnik and Valenta are much more readily soluble than the ordinary Syrian asphalt. In developing one must go carefully to work, and not allow the turpentine to stay on the stone a long time, but to pour it over the stone, which should be inclined so that it can run off. This can be repeated if required. It can be well and safely developed if half and half of turpentine and linseed oil is used, which, however, has the disadvantage that the stone becomes greasy, but this can be taken off by the expert printer. ”

“ When a photo-lithograph like a pen and ink drawing is to be prepared from a coloured picture, or from a sepia or Indian ink wash drawing of a plastic object or a photograph from nature, or from an object not suitable for photographic reproduction an autotypic transfer is to be prepared, a proof of the desired object must be first prepared, and then from this the drawing is to be made. ”

“ Gustav Suckow, in his work, “Die chemischen Wirkungen des Lichtes,” stated that the chromate salts were also sensitive to light in the absence of silver if an organic substance was added, as in the light lower (green) oxidation products were formed. In 1839 Ponton added to Vauquelin’s and Suckow’s discoveries, and discovered the photographic application of chromate of silver, the light-sensitiveness of potassium bichromate on paper. ”

“ Insensitive asphalt behaves in the same way. With correct exposure under a clear negative of about 20 degrees Vogel, and subsequent development and auxiliary exposure for about half to one hour, the drawing adheres firmly to the stone. If the image is to be washed off, the turpentine must act for five to ten minutes on the film, till the exposed asphalt has dissolved. If, after washing off, it is inked up, all the places take the ink well, and the image appears clear and plain. The image can only be destroyed by strong acids or alkalies, which actually dissolve the stone itself. ”

“ The stone is now, according to the sensitiveness of the film and the strength of the light, exposed for from fifteen minutes to two hours. Over-printing, if it is not very exorbitant, does not do any harm with the stronger letters or lines on account of the good covering. With very fine lines, however, more care must be taken. If there is any doubt as to the length of the exposure a test may be made at one corner of the plate with a pad dipped in rectified turpentine. When the asphalt will no longer dissolve the exposure may be discontinued. ”

“ Prints produced by the third method, copper-plate printing, give far greater difficulties to the photo-mechanical worker. Every pull from the engraved plate—etching scraper drawing and photogravure excepted—possesses a tone on its surface, which is, moreover, very unequal, and although increasing its artistic qualities, offers, however, considerable difficulties for reproduction. ”

“ Thin developing inks, which are distributed with a broad brush or a pad, can be prepared by diluting good transfer ink with equal quantities of wax, benzine, and turpentine.
A good developing ink must have the following properties: When spread upon the print must give a clean, sharp, sufficiently dense impression, which can be easily transferred to the plate or stone; on the other hand, the drawing ought not to spread. The transfer should possess such resistance that, without rolling up, it should resist a slight etching. ”

“ Since all lines of the drawing appear in the impression of the same colour, there is not only no purpose, but it may even be very disadvantageous to the reproduction when the draughtsman, in order to increase the artistic effect of his work, or to produce good perspective, etc., draws fine lines or other points in a lighter colour. ”