Volltext Seite (XML)
264 THE PHOTOGRAPHIC NEWS. [April 3, 1891. to facilitate the transfer of the finished print; the simplest and safest for this purpose is talc, or French chalk, to be used thus: Take a piece of old calico, rather fine, pour into it a certain quantity of talc, tie up the corners, and squeeze it all to the centre till you have got a ball as big as an egg ; with this rub the plate all over with a rotatory movement from the centre towards the edges till quite brilliant; the lump of talc can be used over and over again till exhausted. Now take a damp cloth, and pass it round all the edges of the glass to the depth of about one sixth of an inch, so as to remove the talc from the place along which the damp cloth has been passed. Another method is to pass round the edges of the glass, instead of the damp cloth, but to the same depth, a brush dipped in albumen. The plate, having been treated as above, is put into a rack to dry. When dry, take plain collodion as fluid as possible, and, after lightly dusting the surface of the prepared plate, pour the collodion on the plate in the ordinary way, taking care that every part of it is covered, including the edge, off which the talc has been wiped, or brushed over with albumen ; otherwise the print would begin to detach itself in that spot. The layer of collodion should be very fine and transparent. While plates so prepared are put aside to dry, take fine, white sheet gelatine in sufficient quantity for the number of plates to be done, and, placing it in a clean tray, add sufficient cold water to cover it; allow this to soak for some hours, then put it into a saucepan, which stand inside another full of water, placed in a quick fire, and stir it from time to time till thoroughly dissolved. A quart of gelatine prepared as above will cover 250 plates; what is over need not be thrown away, but put aside for future use. When the gelatine is dissolved, filter through very fine linen into a bottle strong enough to stand heat, and, having filled it to the top, wait a few minutes till all the air-bubbles have come to the top, which should be blown off ; then take a very clean dish, which should have one end of it raised by a piece of wood or any other support, and into this pour the gelatine very slowly, so as to avoid air bubbles, until the liquid just covers the raised end. Now take one of the collodionised plates by a corner, and, having the coated surface towards the gelatine solution, rest one end of the plate on the raised end of the dish, and, sup porting the other end on a silver or ebonite hook, gently lower it until the collodionised surface rests on or touches the liquid in the dish, without allowing the gelatine to get on to the back of the plate : then lift up very slowly, and, having drained it for a moment, lay the plate flat on a shelf well protected from dust. Do this in a good light, and very slowly. The plates thus coated should be left to dry for ten or twelve hours in a warm room, and when dry can be stowed away for use, and will keep good for a long time. Plates of a large size should receive at least two succes sive films of gelatine, leaving plenty of time to dry between each coating. The greater the number of films the plate receives, the greater will be the depth, strength, brilliancy, and delicacy of the enamel. This completes the preparation of the plates, which ar now ready to receive the photographs to be enamelled. But before doing anything, see that everything is in its place, so that the work may proceed rapidly and with certainty. To begin with, prepare the following solution:—Gela tine 4 ounces, water 54 ounces; soak the gelatine in the water for some hours, and complete the melting by putting it into a saucepan over a slow fire and stirring it every now and then ; while this is being got ready, place on your left side and within reach the box containing the collodionised and gelatinised plates; near this have a rack to receive the plates after the photographs have been fixed to them, and near by have a stove with a large chop tin dish full of hot water; it will be well to have two handles to this dish, so that when necessary it may be moved off the stove with facility. In the hot water in this dish, stand two porcelain dishes large enough to contain the prepared plates and photographs to be ehamelled. Have ready also a sponge and a squeegee. Now filter the dissolved gelatine into both these dishes, taking care to avoid air-bubbles as much as possible. This done, take the vessel containing the hot water and the two dishes with the gelatine solution off the stove, or the solutions will become too hot, and immerse a few of the prints in the dish on the right-hand side. Then take one of the prepared plates and lay it with the collodionised side in contact with the solution in the left-hand dish. Raise the plate immediately this is done, otherwise the preliminary pellicle will become softened, and, taking one of the prints from the gelatine solution, lay it with its face in the collodionised surface. Hold it in its place, and with a squeegee rub, not too hard, the back of the print to get rid of the excess of gelatine and air bubbles. Turn up the glass, wipe it over with the sponge soaked in warm water, and make sure that there are no air-bubbles ; if any, run the squeegee along the back till they are got rid of. AU these operations should be done quickly, so as not to give the gelatine time to coagulate. Put the plates on the rack to dry. The rack for these plates should have very wide grooves, so as to avoid rubbing the pellicle, which at this stage is very tender and soft. The solution of gelatine should not be too hot, or the prints will turn yellow. If the water in which the dishes containing the dishes with gelatine solution begins to cool before the pictures are all mounted, it must be re-heated. It is difficult to say how long these plates will take to dry. In very hot weather choose a very airy room, and not too warm, in which to dry them. An enamel can never be too much dried ; on an average it may dry in twelve to fifteen hours, but it is best to allow it a longer time. As soon as it is quite dry to the touch, with the point of a penknife cut the pellicle inside the albumenised edge, and insert the knife so as to get hold of the print between it and the thumb, and raise it gently. If sufficiently dry, the pellicle will, in detaching itself, make a dry, hard sound like tearing a piece of parchment or calico. After they are detached, the prints must be kept quite flat. The prints can now be trimmed and mounted as suited to each individual fancy, but care should be taken that the enamelled surfaces are touched as little as possible with the fingers.—Journal of the Photographic Society of India. The Beacon, a photographic journal published at Chicago, is responsible for the following :—Crystallos is a new transparent substitute for glass, manufactured by M. Jumeaux, the great doll maker of Paris, and is said to be the outcome of three years’ work and study, and at a cost of over 300,000 francs. It is not a plagiarism of the Kastman film, not xylonite, nor collodion, nor gelatine, nor rubber. It is simply crystallos, a new material ; bright, pure, transparent, inextensible, splendid, and—perfect; so, at least, says a correspondent; and it is also comparatively cheap, the 6} by 43, coated with a very rapid emulsion, being retailed at about a dollar a dozen.