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Typo: A Monthly Newspaper and Literary Review, Volume 4

Sommer's Overlay Process.—

Sommer's Overlay Process.—

Carl Kempe, in Der Stereotypeur, describes the new process by which Mr Sommer, the overseer of Moser's Court Printing-office, Berlin, brings up his blocks for the machine. The making-ready is done on an overlay consisting of one thick and three thin sheets of post paper, united by a particular kind of thin paste, which is scarcely visible, and which permits the sheets to be fastened flat to one another, and also to be easily separated without tearing the under-sheet. This overlay is placed on the cylinder in the place corresponding to the illustration. If type and pictures are to be printed together, the picture must be kept a little lower than the type, in order to allow for the extra-stout overlay on the cylinder. The overlay having been fixed and the first pull taken, the places which come up too strong are bevelled out—cut out one can scarcely say, as the machine-minder just scratches a cut in the surface with a knife held obliquely, and then separates a thin layer of paper. All the pulls are made on bank-post paper, and the light places on the overlay laid open so far as required to secure clear impressions. When this is finished, the raising of the high places, that is to say, the working-up of the shadows, is proceeded with. This is done with a peculiar solution, painted with an artists' brush on all those places which are to appear prominently. The workman can lay on the coating as thickly or thinly as he pleases, as the solution dries very rapidly, and may be strengthened according to desire. If good printing-ink is used, the effect of an engraving thus brought-up is very striking. The coating has no sharp edges, it bevels or slopes away admirably at the sides, and permits the most delicate shades to be observed. The inventor did not reveal the composition of the solution. Hr. Kempe suggests that it may be (1) shellac dissolved in spirit; (2) gutta-percha dissolved in turpentine; or (3) glue mixed with chromic acid. The invention is very valuable, as, in addition to its advantages from an artistic point of view, it reduces by more than one-half the time of making-ready.