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November 23, 1883.] THE PHOTOGRAPHIC NEWS. 741 requisite transparency. It is then ready to be painted, which operation should not take more than half-an-hour. Dr. Liesegang says on this subject: “ Those interested in the production of crystoleum pictures will find a mixture of two parts of castor oil and one part of spirits of turpen tine very useful for making the prints transparent. If an albumen print is to be mounted on glass, the gela tine or tragacanth solution ought to have some drops of liquid ammonia added, a better contact with glass surface being obtained. Let the mounted print dry, then rub the back of it with emery-paper, and apply the above mixture with a cloth ; after an hour, rub the mixture off with a clean cloth, and coat the paper with thin dammar-varnish. After drying, this surface will take oil-colours easily.” zy-teerbze. HOW TO MAKE AND USE A VELVET ROLLER Three months ago a note came to us from a gentleman, who had practised photo-lithography with more or less success for some time past, touching “The Photographic Studios of Europe.” The letter contained many critical remarks, and one sentence we may here quote: “The best thing in the book is the velvet roller ; it has solved most of my difficulties for me, and I am now a practical photo-lithographer, instead of only an experimentalist.” We take no credit to ourselves in this matter, for the simple reason that our position in connection with the bookin question is more that of reporter than author; but as our correspondent is one only of many who have taken an interest in the velvet roller, we here revert to the subject once more, giving as an additional reason that the employment of this instrument is by no means con fined to the photo-lithographer. It may be used with ad vantage in the application of photographic images to surfaces of wood for wood-engraving, to china or porcelain for burning in, to leather and fabrics for ornamentation, and in fact wherever it is desirable to produce a fatty ink impression in the simplest manner, whether this is for transfer or not. The velvet roller permits of the inking up, with fatty ink, of any photo graph without the aid or paraphernalia of the litho grapher, while it is at the same time an invaluable aid to the latter if he desires to practise the art of photo-litho graphy. The reason why the velvet roller is of value in this connection is easily explained. It is the only roller that may be passed over a print upon bichromated paper with impunity. If you take a sheet of stout paper—bank post is the best, as it is the toughest—and float on a solution of bichromate and gelatine, you make the surface, as every photographer - knows, sensitive to light. This sensitized paper may now be put under a negative and printed. Any negative will yield a print, but as a matter of fact it is not every negative that gives a successful result. Photographs in black and white, or designs sketched in Indian ink lines, or reproductions of wood-cuts, &c., are the only ones that are likely to succeed in the hands of the ordinary photographer or photo-lithographer, for if it is a question of reproducing half-tones, only those familiar with the production of collotypes will make a good job of it. At the same time, if it is but a matter of getting a mediocre impression from a half-tone negative, sufficient for the wood-engraver to work from, then anyone ac customed to ordinary photographic manipulations, if he but proceeds with care, can do all that is required with the velvet roller. The bichromated print is immersed in cold water for three or four minutes, when the soluble salt is discharged, the yellow brown image stands out with more distinctness, and the gelatine elsewhere over the surface becomes swollen with moisture. Taken from the water, the print is now laid smoothly upon a sheet of patent plate glass, which latter shonld be a little narrower than the paper, so that the latter can be folded under the glass and kept firmly in its place. A sheet of blotting-paper is carefully pressed over the surface of the print to take away super fluous moisture, and now - the velvet roller may be passed over the impression to ink it. Naturally, the treatment of a damp paper photograph in this way is a delicate operation, and on this account it is that the best and toughest paper must be employed for the purpose. Again, the velvet roller must be handled with great care. After being charged with ink in the ordinary manner by rolling it upon an inked slab,* the roller is placed upon that part of the print nearest to you, and then rolled from you; it must not be rolled back wards, but simply in one direction, viz., from the worker. Care also must be taken that the seam of the roller does not touch the print, and as a roller four inches in diameter will ink a twelve-inch print without this being necessary, there is no need for such a thing to occur. The ink should be as thin as paint, and should be applied again and again until sufficient body has been obtained. But too little ink is better than too much, especially in fine designs, which require very little. The rolling is done very lightly—unlike in lithography, where considerable pressure is used—but after a little practice the paper print may be manipulated as deliberately as if it were a slab of stone or sheet of zinc. We need hardly say, on the other hand, that if a leather roller were employed, this would not only tear off the delicate photographic im pression from the surface, but would also ruck the paper. Velvet has nogrip, and leaves the paper without pulling. As soon as the impression is suitably inked, your work is done. The inked photograph may either be pressed against a wood block if the picture is to serve the purpose of the wood-engraver, or it may be transferred to stone or set off against canvas, leather, &c. With a little care, and re-dipping the paper print in water, several impressions may sometimes be taken off in this way. But it must be borne in mind that if any work of a lithographic nature be undertaken, the photographer should call in the aid of a skilled lithographer; the former cannot expect in a few experimental trials to do as well as the man ac customed to the work all his life. And now as to the construction of a velvet roller. Here is a sketch showing it complete and in section. The measurements specified arc those to be recommended, and in the section wc show the materials of which the roller is made. After considerable experience, it is found that the best silk velvet is most suitable for the purpose. The body of the roller is of pear wood, a light material most favourable to the purpose, while the handles are of box wood. Over the pear tree block are sewn two layers of thick serge, and over the latter one thickness of velvet, the * We have already given directions in these columns as to the nature of the ink to be used, and its application to slab and to roller. Take two ounces of transfer ink from the pot, add J-ounce of olive oil, mix well together with a muller on slab; this you will find gives a paste about the consistency of butter. Such paste makes capital stock. When the printer is ready to rollup the transfer, reduce the above with turpentine to about the thickness of cream ; you will now find your ink is ready for the roller. Charge the roller liberally, and roll the roller well up on the slab. In so doing, you will find the turpentine evaporate, leaving the ink in beautiful condition for a first-class transfer. Should you find your ink get too stiff, reduce it with turpentine; be sure you roll your transfer one way only— namely, from you.