Photography with Emulsions: A Treatise on the Theory and Practical Working of the Collodion and Gelatine Emulsion Processes

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Page 282 - after which it should be placed in ' weak hypo (1 : 10) until the soluble chloride is dissolved. Ammonium sulphocyanate alone will be found to fix a plate or paper print made with silver citro-chloride emulsion, but hypo is cheaper and quicker. Should the plates or paper be inclined to frill, place them in saturated chrome alum solution after toning ; this in no way affects the colour or purity of the whites. Washing is the same as with other gelatine plates and silver prints.
Page 75 - J which has been previously boiled in hot water to get rid of any grease or dirt. The emulsion is then twisted up in this, and, by a gentle pressure, squeezed through the interstices, the ball of emulsion being absolutely below the surface of the water into which it is forced. The water causes the...
Page 121 - The temperature of the cupboard should be kept as even as possible, sudden changes being detrimental — producing markings. Opening the drying cupboard door before the plates are dry, when once the heat has been turned on, is a mistake ; the plates should be left until it is judged they are quite dry. Very quick drying is also a mistake, as the different layers of the film get an uneven strain, which eventuates in frilling.
Page 144 - A very little experience will enable the operator to produce a good printing negative from a plate which, if developed with the full proportion of A, would have been utterly useless from over-exposure. In very warm, bright weather, it will, perhaps, be found an advantage to use rather more D than A in the mixed developer, giving just sufficient exposure to avoid hardness in the negative. Under-exposure can be corrected to a...
Page 282 - Upon adding the gold, it is converted into a sulphocyanate, which will be seen to have a red colour. The precipitate, however, dissolves in the excess of sulphocyanate, and is then ready for use. Washing before toning is dependent on the formulas employed in making the emulsion; in most cases it will be found advisable.
Page 202 - ... more. If all the bichromate be not taken out by this washing, it is not of much consequence, since, when dry, it is inactive. The sensitiveness after this treatment is not much diminished, and the negatives taken with it are beautifully bright. Plates may be treated in precisely the same manner, and give unveiled pictures. There is a slight diminution of sensitiveness if the bichromate be not all washed out, but nothing to hurt except where very great rapidity is required. Another cure is the...
Page 143 - ... adhere to the surface of the plate, at once remove them with the finger or a camel's-hair brush kept for the purpose. Rock the dish gently, taking care to keep the plate well covered with the solution. In a few seconds the image will appear, and, if the exposure has been well timed, all the details will be out and the development complete in about one minute, when the negative should be well washed under the tap and placed at once in the fixing-bath.
Page 201 - ... hour, and then wash again for a couple of hours more. If all the bichromate be not taken out by this washing, it is not of much consequence, since, when dry, it is inactive. The sensitiveness after this treatment is not much diminished, and the negatives taken with it are beautifully bright. Plates may be treated in precisely the same manner, and give unveiled pictures. There is a slight diminution of sensitiveness if the bichromate be not all washed out, but nothing to hurt except where very...
Page 119 - The plate is then, detached from the pneumatic holder (if used), held by the two corners of the diagonal, and very quietly rocked till an even, coating is seen to be secured. It is then cautiously slipped on the level shelf, and left to set. Another plate is taken and similarly treated ; and when the shelf is full, the emulsion on the first plate will have set, and it must be removed to the dryingrack (page 143), and thence to the cupboard.
Page 75 - ... soluble salts are at once extracted. When all is squeezed through, the particles of gelatine may again be transferred to the canvas, stretched loosely over the mouth of the jar, the emulsion may be doused with water from the tap or from a water-jug, and then left to soak for half an hour.

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