CHAPTER II.MAKING GRAINED NEGATIVES.
For making grained negatives, the apparatus, chemicals, and manipulations described in Chapters I. and II., Part I., for line negatives, are required, with perhaps a little increased care to secure clean and bright negatives.
The first requirement will be a proof, on fine white paper, from a machine-ruled plate, or a plate with fine dots or stipple; a favorite being plates ruled diagonally and straight, either in single lines or crossed. These plates must be of good size, say 18 by 15, ruled with lines as fine as possible, 100 or 150 to the inch. The ruled sheet must be perfect, as any defect in it will be fatal.
Such a proof being secured, it should be carefully mounted with starch paste upon a stout piece of smooth cardboard, and should be carefully shielded from all chances of being soiled, as the slightest stain or mark upon it will unfit it for use. As such a fine line is very difficult to focus, especially in making the smaller screens, it will be found a good plan to cut four narrow strips of good, bold type, and paste these at the four corners of the sheet, just outside the ruling; these slips of type will be easy to focus, and will render the task of making the screens easier.
Plates ruled with single lines, either diagonally or horizontally, may be used instead of the cross ruling, and are by many preferred.
Those in possession of a ruling machine may make these ruled sheets by ruling a large litho stone, and pulling impressions from that stone. If this is done once, and done well, the sheets will last a lifetime; and if the stone be sufficiently large, and the lines very fine, the screens may be used for blocks 15 by 12 inches or larger.
To copy this ruled sheet, remove the mirror from the lens, and put the lens in the camera in its ordinary position; then pin up the sheet on the easel, and, after seeing that the easel and camera are quite parallel, proceed to make a series of negatives from the sheet, making screens of various degrees of fineness, varying from a coarse grain for a coarse photograph, to the finest possible for{66}photographs full of delicate half-tone, and from three inches to ten inches wide. Many subjects will need screens made especially for them. The screens must be free from speck or stain, and should be made upon very thin glass.
The nitrate bath should be in good condition, and the collodion ripe. Such negatives take a good deal of time making, but as they are the foundation of the process, and with care will last for years, the trouble must not be grudged.
The screen negatives being made, they must be varnished with a good, hard, well-filtered varnish, applied in a room quite free from dust.
The screens must be made by the wet collodion process. The ordinary gelatine dry-plate is utterly useless for such work. Gelatino-chloride plates might do, but the exposure is so very long that there is risk of shaking the camera during exposure.
THE GRAINED NEGATIVE.For the first method a good vigorous photograph is selected, placed in position on a copying board, and the camera adjusted so as to get the image on the focussing screen the size wanted the mirror being used, as the negative must be reversed.
For the first method a good vigorous photograph is selected, placed in position on a copying board, and the camera adjusted so as to get the image on the focussing screen the size wanted the mirror being used, as the negative must be reversed.
A collodion plate is now prepared and well drained; then one of the transparent screens is fixed in front of the carrier by drawing pins, by passing strips of gum paper over, or by fixing with fine tacks a piece of thin card at the top, and one at the bottom, slightly overlapping the screen, and holding it firmly in a sort of rebate.
The carrier is now placed in the dark slide, the sensitive plate in its place, the door of the slide closed and fastened.
The exposure is now made in the camera, and if the screen is properly transparent the time will not be very much more than when copying in the ordinary way.
The development of the exposed plate is done by means of the developer given in Chapter I., and the result must have all the details of the photograph, while the lines of the screen must be clear and free from veil.
The negative is washed, fixed in cyanide, washed again and then intensified, first immersing it in the solution No. 1, Chapter I., until bleached, then thoroughly washed and blacked with No. 2 solution, again washed, and varnished with the water varnish, or dried and varnished with benzole varnish.
For the second method we shall require, instead of a paper photograph, a transparency on glass.{67}
The transparency may be made on a gelatine dry-plate by printing in contact with the negative, or an enlarged transparency may be made, either on a dry plate or by the wet collodion process.
The transparency should be made by contact, when the original negative is of larger size than the block required; the enlarged transparency is used if the negative be smaller or the same size as the block.
The development of the transparencies on gelatine dry-plates will be treated of later, but if wet collodion be used, the manipulations will be the same as for negatives, except that the image is in reverse gradations, the lights being clear glass, and the shades dense and black. Every detail in lights, shadows, and half-tones must show distinct and strong.
Fig. 5.
Fig. 5.
For the production of these enlarged transparencies, an enlarging camera will be required, which may be provided by having an arrangement in front of the ordinary camera, fitted like the accompanying figure, consisting of two boxes, one sliding within the other, the negative from which the transparency is to be made being placed in a carrier at B.
In the illustration the sides are shown open, but only for simplicity, as they must be quite opaque. In using such an arrangement, the camera must be brought under the skylight of the studio, and the light reflected through the negative, by placing a large sheet of white paper at an angle of forty-five degrees in front of the negative.
Another and perhaps better method will be to cut a hole in a dark-room at a proper height for the camera, and fix the negative in the hole, then adjust the focus upon the screen, illuminating the negative by means of a reflector fixed at an angle of forty-five degrees.
The transparency being secured, it is varnished, and all blemishes or spots removed by means of a sable brush, and a little carmine color; it is then placed in contact with a suitable screen, and the two together are inserted in the{68}place previously occupied by the original negative. Now adjust the camera so as to get the image on the focussing screen the proper size, and proceed to make a grained negative by the wet collodion process exactly as described in Chapter II., Part I., and above. When a negative containing all the details of the original negative broken up by the fine grain of the screen is obtained, it may be dried and varnished, and then it is ready for printing upon the zinc.
All pinholes, etc., should be stopped by means of a fine sable brush and Indian ink. The printing on the zinc should be done by the bitumen process, Chapter VI., Part I., as the albumen is not nearly so perfect. If, however, the albumen process be preferred, the printing is done in the same way as described in Chapter V., but extra care must be taken, first, that the zinc plate is thoroughly and evenly polished; secondly, that the graining bath is kept weak with plenty of alum in, so as to have the grain on the plate as fine as possible; thirdly, that no speck of dust, dirt, or any air-bubbles be on the film after coating, and that the whirling be effectually done so as to get the sensitive coating as even as possible.
The inking up requires no comment, as it must be done as evenly and thinly as possible, for both line and half-tone.
In development, a little more energetic friction will be necessary, but extreme care must be taken not to abrade the ink surface. Continue the rubbing until all the details are developed, and bear in mind that the finished block will be exactly like the zinc after development.
In printing these half-tone zincs, it often happens (like printing in silver) that to get the best results some portions will require less exposure than others. The best way to stop back any portion or portions, is to cover the front glass of the printing frame with whiting mixed with water to the consistency of thick cream; apply with a rag over the places in the negative, before exposing to light, and at the end of one-third, or in case of very deep shades, one-half the exposure, clean off the whiting and finish the exposure without any obstruction to the light.
The exposure to a grained half-tone negative will be one-half to double as long as a simple line negative.
A perfect print on the zinc must contain all the grain intact, for if there is any break in its continuity, it is of no use to proceed further with it.
The printing in bitumen requires no more comment than to say care is necessary to avoid dust. The smallest speck will be likely to spoil an otherwise perfect print.