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Typo: A Monthly Newspaper and Literary Review, Volume 4

Plastic High Stereo Matrices from Paper are thus produced in Germany:—

Plastic High Stereo Matrices from Paper are thus produced in Germany:—

Kempe's matrix-powder is mixed in the proportion of 2℔ powder to 3 quarts of cold water to a liquid of the consistency of milk. A sheet of brown unsized wrapping-paper is saturated with this liquid, a sheet of copperplate paper laid on it, again saturated with liquid, a sheet of good tissue-paper, then a sheet of copperplate paper, and finally seven sheets of tissue-paper, one after the other. The tissue-paper should not be soaked too much with the paste; it is sufficient if the different sheets adhere to each other. The form is thoroughly cleansed with benzine or kerosine, and if the chases are also cleaned, does not require oiling. The matrix is then laid on the form and beaten slowly and gently in with as soft a brush as possible. The beating-in will require at least half-an-hour. The white gleam which penetrates through the brown paper will enable one to judge of the depth of the matrix, so that the usual lifting of the latter is unnecessary. The matrix is then stopped out with little bits of card, stuck on singly with magnesia or matrix-powder; a separate sheet of brown paper, well coated with paste, is now laid on, and beaten in cautiously and patiently till the white shines through. Then the matrix is covered with blotting-paper and blanket as usual, and placed in the drying-press. After ten minutes the blotting-paper and blanket are replaced by fresh layers, and in another ten or fifteen minutes the matrix will be dry and can be prepared for casting. In any case let the matrix remain in the drying-press ten minutes after the form has been removed, in order to steam thoroughly dry. After the casting-paper has been pasted on and dried, the matrix is carefully dusted over with talc or black-lead, and all superfluous material tapped off. After putting the matrix into a very hot oven and closing the latter, wait at least ten minutes before casting, so that the matrix may acquire the same temperature as the oven. The cast should be made in the coolest possible condition of the metal; after the first casting the matrix should only show a very slight yellow tinge. The separation of the matrix also requires patience, for so deep a mould will not allow of being lifted like a loose sheet of paper. Keep on knocking with a key or knife against the projecting edges of the cast all round it, and do this until the matrix springs up of itself. This has to be waited for rather a long time, but patience will be rewarded—the work is sure to be good. When the matrix is taken off, it is talced or blackleaded again, and the casting can be continued as required. We possess matrices which have stood ten faultless castings of depth and sharpness equal to plaster, and are still uninjured. People who are not deterred by the tedious work will be delighted with the deep sharp castings—even the chase is visible—so that the depth just reaches pica.