PLATINOTYPE PAPER.
The platinotype process was discovered a long time ago by Sir John Herschel, but it is not till within a few years that it has come into general use for photographic prints. The paper has been brought to such perfection, and the working made so simple, that the young amateur will find no trouble in using it when he wishes to make specially fine prints.
While one may sensitize the paper, it is better to buy the ready prepared, and as it is packed in tin tubes, the joint being made as near air-tight as possible, it will keep for a long time, especially in a dry climate.
The paper is of a lemon-yellow color, and it prints about three times quicker than albumen paper. Gas-light or a weak white light will not affect the paper, and it may be adjusted in the printing-frames in an ordinary lighted room away from the windows.
To print, place the negative and paper in the printing-frame in the usual manner, and expose to diffused daylight—that is, in the shadow of a building or at a window, but not in sunlight. The image is faintly printed, and then developed. After two or three minutes examine the print, and if the image is well defined, with detail showing in the middle tones, the picture is printed enough. The color of the printed image will be of a grayish-orange tint, and will not appear as distinct as on aristo or albumen, which are printing-out papers.
The developer for platinum prints comes in bulk, with directions for preparing, and better results are obtained by using the prepared developer, especially for the first few times of making platinotypes.
Dissolve the contents of the box of developer according to directions, and place in a tightly stoppered bottle. This is the stock solution. Make a clearing bath of 60 oz. of water and 1 oz. of muriatic acid (chemically pure).
The prints may be either developed by floating them in the developing solution, or the prints may be laid on a sheet of glass and developed by the "brush" process. The latter is better for small prints.
To develop by floating the print, place the print, exposed side down, in the developer by letting it slip evenly and quickly into the solution. Lift and see if any air-bubbles have formed on the surface of the print. If there are any, touch them with the tip of the finger or the corner of a card, and return the picture at once to the developer. The picture will develop quite fast, but it can be stopped at once by transferring the print to the acid bath.
The developer must be used in a porcelain or agate tray, and another tray—a glass tray such as is used for hypo will do—must be filled with the acid clearing bath so that the print may at once be placed in it as soon as it has been developed enough.
As soon as the print has developed enough remove at once, before washing, to the acid clearing bath. The prints must have three changes of the acid bath, leaving them in ten minutes each, and afterward wash them in three or four changes of water, lasting about half an hour altogether. Pin up to dry, blotting off the superfluous moisture with clean blotting-paper.
Developing with a brush is sometimes to be preferred to floating. Take a wide flat camel's-hair brush, turn some of the developer in a shallow dish, lay the print on a sheet of glass, face up, dip the brush in the developer, and beginning at the top of the print, brush it across from one side to the other, and then lengthwise of the print, using light even strokes. The picture will not be so evenly developed as by floating, but this unevenness may be remedied by floating the print for half a minute in the developer and then transferring quickly to the acid bath.
Stop the development as soon as the right depth has been brought out, and while the detail is perfect. If a print is developed too long the print will appear flat, as in the case of a negative when overdeveloped.
As platinum prints are more quickly made than aristo or albumen, this paper is very desirable for winter photographic printing.
The mounts for platinum prints have a plate sunk centre covered with India paper, and are usually of a soft gray color for the margin. The prints may be mounted on plain cards, but are much more effective if mounted on the cards prepared expressly for platinotypes.
The paper costs 50 cents per dozen for 4x5, 80 cents for 5x7. The paper can be bought in any size desired. The developing solution or salts cost 35 cents for a package containing enough to make 50 oz. of developer.
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