In copying paper photographs the granular texture of the paper invariably injures the copy, making it appear to be covered with whitish dots. A method practised by Denier, a Russian photographer, enables one to obtain a perfect copy in which all granularity is avoided. On copying the original it is illuminated with a strong side light, so as to minimise the grain as much as possible to begin with. The negative is made tolerably vigorous, and then slightly retouched. In printing (using a registering printing frame), when the impression has attained somewhat about half its proper depth, it is removed from the negative, and a couple of thin films of gelatine - such as those used in packeting confectionery - are placed upon it, one of those films being tinted a pale blue, and the other colourless. The half-printed sheet is next replaced over the gelatine sheets in exactly the same position as it previously occupied, and the printing is continued until it is dark enough. By this method, the details are printed first, while the second printing blurs and softens the picture, and prints out the granularity.
An ordinary printing frame may be converted into a registering frame by placing a piece of sheet glass in the front, and laying upon the negative, which must have one corner and two sides abut against the interior sides of the frame. The other edges of the plate should be wedged between the sides of the frame. The negative being rigidly secured, the paper must be cut so that its top and one side, at least, shall form exactly a right angle. In replacing the paper in the frame, if care is taken that the 2 edges accurately fit the corner of the frame, it may be removed, the films inserted, and the paper again replaced, provided that the same edges strike the sides of the frame, without interfering with the result or over-blurring the picture. Very soft and peculiar effects may be produced by this process.
Another method is to place the photograph in a strong side light, and in making half the time of exposure with the image exactly in focus on the ground glass, then capping the lens and moving the back of the camera slightly within the focal point, so that the image will be a little out of focus; then to expose one quarter of the time, recap the lens, and expose the last quarter with the rear of the camera slightly beyond the focal point. A negative will be produced in which all appearance of granularity is destroyed, and from which prints may be made direct without the necessity of double printing.