Volltext Seite (XML)
THE PHOTOGRAPHIC NEWS, Vol. XXIX. No. 1386.—March 27, 1885. CONTENTS. PAGE Another Block Process 193 Floral Borders for Photographs 193 A New Developer Containing Sulphite of Ammonia, with a Note on the Lime Developer. By Dr. Joseph Maria Eder 194 The Cruise of the Ceylon^ 1885. By Norman May 194 Blisters on Silver Prints. By W. M. Ashman 196 The Glass House—How to Design, Construct, and Furnish It. 197 Patent Intelligence 199 Gelatine Emulsions, and How to MakeThem, By W. Deben- ham 201 PAGE Notes 199 Some Recent Experiments in Emulsion Photography. By A. L. Henderson 203 A Few Stray “ Shots ” in Ireland. By Adolph W. Beer 204 Lessons Derived from Pin-hole Photographs. By Barnard S. Proctor 205 French Correspondence 206 Proceedings of Societies 207 Talk 20S Answers to Correspondents 208 ANOTHER BLOCK PROCESS. We have received a sample block made by the process of Mr. George Sutherland, of Adelaide, South Australia, and here is a print from it. The process of Mr. Sutherland is, like many of the pro cesses introduced of late, based on the general principles of the Ives method—that is to say, pressure between a photo-relief and a mechanically-grained surface — and some details gathered from the specification (No. 9026, a.d. 1884—Gardner; a communication from G. Suther land, Adelaide) will interest our readers. A plaster cast from an ordinary swelled gelatine relief is taken (for one of the most convenient methods of doing this see “Photographic Bas-Reliefs,” present volume, page 166), and the further details of Mr. Sutherland’s mode of working will be best elucidated by quoting the actual words of the specification :— “ I rub the surface of the cast first with a small quantity of common gum solution, and then with gold size, made of linseed oil, boiled to a sticky consistency. The relief is then ready to receive the film, impressed with the form of an engraved sur face. This film is prepared as follows :—I take a sheet of tin foil, or any other material which will readily take the form of any surface on which it is pressed, and place it on the surface of an engraved block of wood, metal, or any other suitable material. The engraved block has raised lines, dots, or other marks ar ranged regularly, so as produce, when printed'from, in an ordin- ary typographic surface printing press, the effect of an even shade or tent. The tinfoil or other material having been placed on the surface of the block, is covered with a piece of woollen cloth, and submitted to pressure until an exact impression of the engraved surface has been communicated to it. I then remove it from the block and place it on the prepared surface of the plaster cast, the dots, lines, or other marks being uppermost. A piece of soft woollen or flannel cloth having been again placed above the tinfoil or other material, I submit the whole to a gentle pressure until it has taken the form of the surface of the plaster cast, yet without having the dots, lines, or other marks obliterated. The surface then presents the appearance of a series of raised eminences, of which the highest are situated on the raised portions of the plaster cast, that is to say, on the por tions of the picture which are darkest, the middle tints being partially raised, and the lightest points lying in the depressions. I then gently rub the surface with any instrument having a smooth even surface, such as the handle of an ordinary lead pencil laid flat, and passed backwards and forwards, or a slab of glass, metal, or other material pressed gently on the raised dots, or lines, or other marks. The effect is, that those portions of the surface of the tinfoil or other material which have the highest eminences receive the greatest pressure, and consequently those raised marks on those portions are most flattened out, the inter mediate elevations having the raised marks flattened in propor tion to their height. The pressure and rubbing are continued until on those portions of the surface which are intended to be capable, in the finished block or plate, of printing pure black or the darkest shade, the dots become merged into one another. The surface thus produced is capable of being printed from, but is not strong enough to yield many impressions. I therefore take from it a cast, either in plaster of Paris, or in other suitable material, aud make either a stereotype or an electrotype in the ordinary manner. “ If the type metal or copper or other surface so produced does not print a sufficiently dark picture, either in whole or in part, I rub the surface with a flat piece of wood to which a piece of emery cloth has been attached, or with any other flat or straight instrument suitable for grinding, filing, or pressing metals.” FLORAL BORDERS FOR PHOTOGRAPHS. The paper on producing floral borders for vignette photo graphs, recently read by Mr. R. E. Freeman before the Newcastle-on-Tyne Photographic Association, brings to mind some very elegant examples of work in this direction
