The photographic news

• Bandzählung: 12.1868
• Erscheinungsdatum: 1868
• Sprache: Englisch
• Signatur: F 135
• Vorlage: Hochschule für Grafik und Buchkunst Leipzig
• Digitalisat: Hochschule für Grafik und Buchkunst Leipzig
• Digitalisat: SLUB Dresden
• Rechtehinweis: Public Domain Mark 1.0
• URN: urn:nbn:de:bsz:14-db-id1780948042-186800009
• PURL: http://digital.slub-dresden.de/id1780948042-18680000
• OAI: oai:de:slub-dresden:db:id-1780948042-18680000
• Sammlungen: LDP: Historische Bestände der Hochschule für Grafik und Buchkunst Leipzig
• Sammlungen: Fotografie
• Strukturtyp: Band

• Digitalisat: SLUB Dresden
• Strukturtyp: Ausgabe

THE PHOTOGRAPHIC NEWS. [July 3, 1868. side downwards. The plate is then placed, face upwards, on a table, and the surface is scraped with a razor-blade inserted in a groove in one end of a flat wooden handle. To make this tool, take an ordinary razor, break off the tang, and fix the blade into the groove in the handle ; sharpen it by grinding it vertically on an oil-stone ; by this means the blade receives two scraping edges, both of which may be used before re-sharpening. This tool is held with both hands, thumbs in front, pointing up. The plate is scraped evenly all over in parallel lines till all the inequalities have been taken off and the surface appears tolerably smooth and bright all over. It is then examined for holes and other serious flaws, which must be hammered out. The position of the hole is marked on the back of the plate by means of a pair of callipers, which may be made of a strip of hoop-iron with a hole at each end, and doubled so that the hole corresponds exactly one over the other. One hole is placed over the flaw, and a mark made on the back of the plate through the other hole. The plate is then laid, face downwards, on a very smooth steel anvil, and the back of the plate is hammered at the spot indicated by the pencil mark till the face is perfectly smooth and the flaw removed. The hammer-head has a flat face at one end, and is round at the other; the anvil is of steel, about 4 inches in diameter, and is fixed into a strong wooden block. They are to be obtained at the tool shops where engravers’ tools are sold. The scraping is continued till the surface is uniform. The plate is then removed to the graining-trough and rubbed with pumice-stone lengthwise and crosswise in parallel lines till it is perfectly smooth. The pumice should not be too hard, or it will cut deep scratches in the plate, which will be removed with difficulty. The softer it is the better ; if it works gritty, which can easily be felt, the plate should be washed and the pumice cleaned with water. When the plate is quite smooth, and all furrows and markings have disappeared, it is smoothed with Water-of- Ayrstone, or, as it is commonly called, snake-stone. This is worked in the same way as the pumice-stone, the plate being occasionally washed with water. When the plate is quite smooth, bright, and free from scratches, it is fit for graining, which is done by sprinkling fine graining-sand upon the plate, with enough water to moisten it, and working it with azine muller round and round with a slow, consecutive, rotary motion, in small circles, up and down and across the plate in every direction, till the surface appears of an uniform dark grey tint. The sand used for this purpose is the soft, yellow, loamy sand called brassfounders’ moulding sand. Silver sand is not suitable for this purpose; it is too hard, and liable to scratch the plate. Before use it should be carefully sifted through brass-wire sieves varying in fineness according to the effect required : for common work sieves containing from 80 to 120 holes to the linear inch may be used; for close, fine work, 140 holes ; and for half-tones, where a very fine grain is required, 160 holes. It can be bought ready sifted, of different degrees of fineness, and may be preserved in bottles with a small hole in the cork. The mullers are of different shapes, but it is essential that the sharp edges should be rounded off with a file. There are three kinds of mullers in use, as shown in the annexed diagrams. Fig. 1 is a solid, Fig. 1. Fig. 2. Fig. 3. Fig. 4. conical mass of zinc, with a base of about 4 inches diameter ; fig. 2 is a disc of zinc 4 inches diameter, 2 inches thick, fastened to a wooden or iron handle. To cast them, a mould is made in sand, the iron handle is suspended over the centre of the mould with a piece of string, the melted zinc is then poured in, and, when cold, is faced and turned in a lathe. No. 3 is a simple and cheap form ; it consists of a large bung, on the base of which a square piece of sheet zinc is laid, the sides turned over and pressed towards the circumference of the bung. The corners are cut away and turned up. Owing to slight inequalities there frequently remain strips or patches on the plate which are not granulated; these should be worked with small mullers, as fig. 4. While graining the greatest care must be taken to avoid getting any grit on the plate. The mullers should be carefully washed before use, and while in use should not be put down on their faces or where any grit or dirt may attach itself to them. When the sand first applied has become too fine, and is of a dark slate colour, it should be washed off, and fresh sand applied. In the course of from half an hour to two hours the plate should appear of an uniform grey colour, finely granulated, and may be considered ready for use; it is well washed with water and a soft flannel kept for the purpose, till all traces of the sand are removed, and then turned up on its edge to drain. Hot water is then poured over the back of the plate, so that the face may dry as quickly and evenly as possible. The plate is then carefully stowed away in a dry place till required for use. The greatest care must be taken not to touch grained plates with the fingers, and to keep them from anything greasy. A plate is in its best condition when first prepared; by keeping it gradually deteriorates, and should not be used after it has been kept a fortnight. Treatment of Zinc Plates which have received Transfers. The zinc plates can be regrained, and used over and over again, without any sensible diminution of thickness. The regraining is a very simple operation, and not so trouble some as the first preparation of the plates. If the plate to be regrained is “ gummed up ”—that is, covered with gum to preserve it—wash off the gum, remove the ink with tur pentine, wash clean with water, and apply the Alkaline Solution. Potash 4 pounds Quicklime ... ... ... ... 4 „ Water 6 gallons A strong solution of common potash will answer. Tha object of this is to destroy the grease in the ink. Wash well with water, and with a flannel rubber apply an acid solution :— Water... ... ... ... ... 2 ounces Sulphuric acid 2 drachms Muriatic acid 2 „ Let this remain for a few minutes, and then wash well with water. This should be done in the open air, as the fumes arising are very unpleasant. The plate is then treated and grained as before described. {To be continued.) MR. PIERCY’S PATENT METHOD OF ARTISTIC PRINTING. We recently noticed some very fine examples of artistic printing by Mr. Frederic Piercy, a gentleman well known in art circles as a skilful painter. We subjoin the specification of the method whereby the results are obtained. The appli cation of lithography to photographs, as our readers know, is not new; the novelty here consists in the mode of regu lating the tint, and giving it a certain amount of pictorial gradation, by removing portions from the stone or plate before printing ; in the mode of obtaining texture and modelling by manipulating on the applied tint with bread or india-rubber; and of obtaining sharp lights by burnishing at the back of the tracing or print placed on the inked stone previous to printing the tint on the photograph to be treated. The effect obtained by working on and graduating the delicate grey ink which is applied to the photograph gene-